Yes.
I don't think that's solved yet.
I think the easiest way forward for Wilhelm, is to make routines to allow copying data from a ROM bank above the compiled and banked 2.9, to either VDP or RAM. Care must be taken to ensure, that you do not overwrite bits that make the compiled program run. After MAKECART8 you append your databanks to the end of the cartridge. The edit-compile-test cycle by which a programmer iteratively remove errors becomes somewhat longer and more complex, but not impossible. I suggest you try out Assembly. There's a learning curve different from person to person. You could use 2 weeks or 2 years to get where you are today with your current game development project.
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