Is there a good tutorial for how to use nightmare modules with FE4

Questions
1

Hey, I have some experience with sacred stones hacking, and I decided I wanted to go back and mess around with my favorite game, maybe try to create a 0% growths rom or negative growths rom if possible. I loaded up the character editor and went to Sigurd, and it’s displaying all kinds of wrong info. It’s saying his class is dragon master, he has 70 base strength, 0 base hp, etc. Is there some sort of intermediate step I missed besides just throwing the rom into Nightmare? This is a base, Japanese version of the Rom with no prior edits btw.

Edit: I tried both nightmare versions and both consistently gave me the same wrong info

Thanks for any help

3

SNES ROM converter: smc to sfc (smc2sfc.herokuapp.com)
or
SMC(SFC/SNES)ヘッダの付加・削除システム - エミュレータ情報局 (web-g-p.com)

4

Okay, I messed about a bit and fixed the incorrect data issue. Only SMC files are working.

In this, however, I also found a much bigger issue. I literally only changed the growths of playable characters and holy blood to 0, and it somehow corrupted the file twice. Any ideas on how to fix that?