Currently the commitTransaction command only gets the TransientTransactionError label on a smaller set of error codes than most other commands within transactions (see https://github.com/mongodb/mongo/blob/8956deeef7bd4013d3de4092374fb9a2c329e2a5/src/mongo/db/handle_request_response.cpp#L49).

There's no reason for this, however. commitTransaction should be able to get the TransientTransactionError on all the same codes as every other transaction command, with the one exception of NoSuchTransaction in the case of a writeConcern error (see SERVER-37179)