The Edit tool now attempts to match \uXXXX escape sequences and their literal Unicode character equivalents. If neither form matches, it provides a more helpful error message: "Edit also tried swapping \uXXXX escapes and their characters; neither form matched, so the mismatch is likely elsewhere in old_string.".
Evidence
Unicode swap functions $e8 and qe8 at line ~260927, and error hint (search for "swapping \\uXXXX escapes").
Strings lifted out of the shipped bundle, so the claim above can be checked against them.