diff --git a/schema/message_fmt2/testgen_schema.json b/schema/message_fmt2/testgen_schema.json
index e3f9e6e4..a329bd34 100644
--- a/schema/message_fmt2/testgen_schema.json
+++ b/schema/message_fmt2/testgen_schema.json
@@ -68,14 +68,15 @@
         },
         {
           "properties": {
-            "tests": {
-              "type": "array",
-              "items": {
-                "required": [
-                  "src"
+             "tests": {
+               "$comment": "type: array provided for clarity only",
+               "type": "array",
+               "items": {
+                 "required": [
+                   "src"
                 ]
-              }
-            }
+               }
+             }
           }
         }
       ]
@@ -148,6 +149,9 @@
         "params": {
           "$ref": "#/$defs/params"
         },
+        "comment": {
+          "$ref": "#/$defs/comment"
+        },
         "exp": {
           "$ref": "#/$defs/exp"
         },
@@ -160,6 +164,18 @@
         "expErrors": {
           "$ref": "#/$defs/expErrors"
         },
+        "ignoreCpp": {
+          "$ref": "#/$defs/ignoreCpp"
+        },
+        "ignoreJava": {
+          "$ref": "#/$defs/ignoreJava"
+        },
+        "char": {
+          "$ref": "#/$defs/char"
+        },
+        "line": {
+          "$ref": "#/$defs/line"
+        },
         "only": {
           "type": "boolean",
           "description": "Normally not set. A flag to use during development to only run one or more specific tests."
@@ -171,8 +187,17 @@
       "type": "string"
     },
     "src": {
-      "description": "The MF2 syntax source.",
-      "type": "string"
+      "oneOf": [
+        {
+          "description": "The MF2 syntax source.",
+          "type": "string"
+        },
+        {
+          "description": "The MF2 syntax source, as an array of strings to be concatenated.",
+          "type": "array",
+          "items": { "type": "string" }
+        }
+      ]
     },
     "params": {
       "description": "Parameters to pass in to the formatter for resolving external variables.",
@@ -219,6 +244,10 @@
         }
       ]
     },
+    "comment": {
+      "description": "A human-readable comment, meant to be ignored by the test runner",
+      "type": "string"
+    },
     "exp": {
       "description": "The expected result of formatting the message to a string.",
       "type": "string"
@@ -351,17 +380,32 @@
               "unresolved-variable",
               "unknown-function",
               "unsupported-expression",
-              "invalid-expression",
-              "operand-mismatch",
-              "unsupported-statement",
-              "selection-error",
-              "formatting-error",
-              "bad-input"
+              "bad-selector",
+              "bad-operand",
+              "bad-option",
+              "bad-variant-key",
+              "unsupported-statement"
             ]
           }
         }
       }
     },
+    "ignoreCpp": {
+      "description": "If present, ignore this test when testing ICU4C. The string is an explanation of why the test doesn't pass.",
+      "type": "string"
+    },
+    "ignoreJava": {
+      "description": "If present, ignore this test when testing ICU4J. The string is an explanation of why the test doesn't pass.",
+      "type": "string"
+    },
+    "char": {
+      "description": "Optional character offset that should appear in syntax error. Only used by ICU4C currently",
+      "type": "number"
+    },
+    "line": {
+      "description": "Optional line number that should appear in syntax error. Only used by ICU4C currently",
+      "type": "number"
+    },
     "anyExp": {
       "anyOf": [
         {
diff --git a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/date.json b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/date.json
index 472b46d8..8252ab8b 100644
--- a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/date.json
+++ b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/date.json
@@ -11,7 +11,7 @@
       "exp": "{:date}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -20,7 +20,7 @@
       "exp": "{|horse|}",
       "expErrors": [
         {
-          "type": "operand-mismatch"
+          "type": "bad-operand"
         }
       ]
     },
diff --git a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/datetime.json b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/datetime.json
index 18e0cd97..677a3853 100644
--- a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/datetime.json
+++ b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/datetime.json
@@ -11,7 +11,7 @@
       "exp": "{:datetime}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -26,7 +26,7 @@
       ],
       "expErrors": [
         {
-          "type": "bad-input"
+          "type": "bad-operand"
         }
       ]
     },
@@ -35,7 +35,7 @@
       "exp": "{|horse|}",
       "expErrors": [
         {
-          "type": "operand-mismatch"
+          "type": "bad-operand"
         }
       ]
     },
diff --git a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/number.json b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/number.json
index 515600c4..dc552d32 100644
--- a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/number.json
+++ b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/number.json
@@ -22,34 +22,34 @@
       "exp": "hello {|foo|}",
       "expErrors": [
         {
-          "type": "operand-mismatch"
+          "type": "bad-operand"
         }
       ]
     },
     {
-      "src": "invalid number literal {.1 :number}",
+      "src": "invalid number literal {|.1| :number}",
       "exp": "invalid number literal {|.1|}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
     {
-      "src": "invalid number literal {1. :number}",
+      "src": "invalid number literal {|1.| :number}",
       "exp": "invalid number literal {|1.|}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
     {
-      "src": "invalid number literal {01 :number}",
+      "src": "invalid number literal {|01| :number}",
       "exp": "invalid number literal {|01|}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -58,16 +58,16 @@
       "exp": "invalid number literal {|+1|}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
     {
-      "src": "invalid number literal {0x1 :number}",
+      "src": "invalid number literal {|0x1| :number}",
       "exp": "invalid number literal {|0x1|}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -76,7 +76,7 @@
       "exp": "hello {:number}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -139,7 +139,7 @@
       "exp": "bar {$bar}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-option"
         }
       ]
     },
@@ -154,7 +154,7 @@
       "exp": "bar {$bar}",
       "expErrors": [
         {
-          "type": "bad-input"
+          "type": "bad-operand"
         }
       ]
     },
@@ -189,7 +189,7 @@
       "exp": "bar {$foo}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-option"
         }
       ]
     },
@@ -204,7 +204,7 @@
       "exp": "bar {$foo}",
       "expErrors": [
         {
-          "type": "bad-input"
+          "type": "bad-operand"
         }
       ]
     },
@@ -340,26 +340,6 @@
       ],
       "exp": "other"
     },
-    {
-      "src": ".input {$bar} .match {$bar :number} one {{one}} * {{other}}",
-      "params": [
-        {
-          "name": "bar",
-          "value": 1
-        }
-      ],
-      "exp": "one"
-    },
-    {
-      "src": ".input {$bar} .match {$bar :number} one {{one}} * {{other}}",
-      "params": [
-        {
-          "name": "bar",
-          "value": 2
-        }
-      ],
-      "exp": "other"
-    },
     {
       "src": ".input {$none} .match {$foo :number} one {{one}} * {{{$none}}}",
       "params": [
diff --git a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/time.json b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/time.json
index 4c5dd22b..201f8fad 100644
--- a/testgen/icu75/message_fmt2/message-format-wg-tests/functions/time.json
+++ b/testgen/icu75/message_fmt2/message-format-wg-tests/functions/time.json
@@ -11,7 +11,7 @@
       "exp": "{:time}",
       "expErrors": [
         {
-          "type": "invalid-expression"
+          "type": "bad-operand"
         }
       ]
     },
@@ -20,7 +20,7 @@
       "exp": "{|horse|}",
       "expErrors": [
         {
-          "type": "operand-mismatch"
+          "type": "bad-operand"
         }
       ]
     },