The patch doesn't seem to work. It overwrites all rombank numbers at 0x4000 from rombanks 0x22 on it seems. With that fixed vblank code won't switch back to the wrong rom bank. However, the text is overwriting itself and looking very messed up in the naming screen. You probably do something wrong in your code that the hardware doesn't support or you expect to work differently.
I tested in BGB with the accurate emulation settings on. Here's what I get:
I hope you can fix that so it will be a fully working release
Also: No readme? What's up with that?