I am not sure why you still don't have codehandleronly.bin after all of these years included in Dolphin. It does work if you replace codehandler.bin with it. codehandleronly.bin supports about 400 codes compared to the default 231. I will link to it after I get it uploaded. There is source code available at
https://github.com/FIX94/Nintendont/blob...dleronly.s.
Well, you can always submit a PR if you want to see it included. I don't know if it will be included, but if you do not even submit a PR, it's likely no one knows about it (or cares enough to propose it).
If you have a code handler that supports more codes than the current one, I'd definitely submit a PR for it. If there are no issues with it, I see no reason it wouldn't be approved.
I don't have a github account