Chris,
The only engine specs it leaves open for edit are ones which have not been added to the Raildriver's database of enginespecs which is simple to do. For the record it also worked fine with steam enginespecs in TS12 until SP1. A partial fix for this was released (very promptly) by N3V, but the reverser still does not work and any pleas I have made since for clues as to when/if this issue will be resolved have been diligently ignored. Fingers crossed it will be fixed in HF4.
Regards,
Anthony