This site describes solve-engine as it is on main: 2.43.0, which npm does not have yet. npm installs 2.40.0, so a page may show an answer that version does not give yet.

RenameRefusalCode

type RenameRefusalCode =
  | "RENAME_NOT_A_VARIABLE"
  | "RENAME_GLOBAL_NAME"
  | "RENAME_INVALID_NAME"
  | "RENAME_KEYWORD"
  | "RENAME_UNIT_NAME"
  | "RENAME_NAME_TAKEN"
  | "RENAME_CHANGES_MEANING"
  | "RENAME_NO_ENGINE";

Defined in: packages/engine/src/language/DocumentReferences.ts:135

Why a rename was refused.