Only two of the five new fixture output.json files differ from the original Babel 8 commit, and both are expected Babel 7 AST differences — not bugs.

1. typescript/TSEnumBody-trailing-comma/output.json ✅ correct

• Original (Babel 8): TSEnumDeclaration.body = TSEnumBody { members: [...] }
• Cherry-pick (Babel 7): TSEnumDeclaration.members = [...] (flat, no TSEnumBody wrapper)

Babel 7 has no TSEnumBody node — members live directly on TSEnumDeclaration. The trailing comments still land on the correct TSEnumMember, which is the point of the fix. This works because your conflict resolution in comments.ts:209-215 added a case "TSEnumDeclaration" arm that routes to node.members! when !BABEL_8_BREAKING, where the upstream commit removed that arm entirely.

2. typescript/TSTypeParameterDeclaration-trailing-comma/output.json ✅ correct

• Original (Babel 8): TSTypeParameter.name = { type: "Identifier", name: "T", ... }
• Cherry-pick (Babel 7): TSTypeParameter.name = "T" (string)

In Babel 7, TSTypeParameter.name is a plain string, not an Identifier node. The trailingComments and the extra.trailingComma: 20 are attached to TSTypeParameter exactly as in the original — so the fix behavior is preserved.

3. TSInterfaceBody-trailing-comma, new-expression-no-argument, new-expression-trailing-comma ✅ byte-identical

No AST shape differences between Babel 7 and Babel 8 for these nodes.

Code changes

• schema.json and comments.ts additions match the original commit exactly (NewExpression, TSTypeParameterDeclaration, TSInterfaceBody arms + PartialApplicationPluginOptions). The only extra piece is the TSEnumDeclaration compat arm required for Babel 7, which is correct.
• All 16,761 parser tests pass.