OK, then hooking it is.
I have few errands to attend now with few phone calls, in other words will be busy for few hours, but the solution is very easy as i think a simple hook for RegisterClassW/RegisterClassExW/RegisterClassA/RegisterClassExA and changing the ClassName will do the trick with the screen reader.
One thing though, i might didn't understand it right, you need the fix for Delphi 5 application?
If yes then the approach will still doable but will need some cut corners, i would go with using the great DDetours library from
https://github.com/MahdiSafsafi/DDetours , alas it doesn't support Delphi 5, so either the hooking will be less general or a
DLL can solve this easily.
Do you have problem in adding a small
DLL to benefit form the wide range compatibility in hooking ? (in case Delphi 5 is the one needed)
By adding, i mean this
DLL could copied to the system directory and for any or all of your application, all what you need is add one
unit to uses without adding any code, also this
DLL could be tweakable without rebuilding, like using one line in your application to change any ClassName, not just TMyRichEdit.