> I have tweaked that fixer to handle the pointed cases 
> and a few additional ones too

Playing whack-a-mole with a few cases will always fall short of being able to guarantee correct transformations and not break existing code that is working correctly.

One possibility is to add a type check to the generated code, "send(x)" -> send(x.encode() if type(x)==bytes else x)" but this has its own issues and isn't satisfying.