Man you're taking a huge risk just to play games that works perfectly in their NTSC-U counterparts.
But yeah, I understand... I guess.
As far as I know Japanese Wads aren't working fine in American Consoles.
I have StarBlade which is Japanese Exclusive, installed in my NTSCU console.
There's a patch to make the font back to normal because it won't display properly.
It requires to get the StarBlade.wad file, break it down, install the patch, and put it back together to a functional wad file once again.
I think it might be a solution for what you want to do, BUT don't ask me how, nor where to get the patches for these wads... I don't think someone else has actually created patches for these specific Japanese wads. But I might be wrong about this last part, I mean, the internet is a pretty big place, and it's something you could do yourself with the appropriate tools... I think.
Info about StarBlade patching:
https://gbatemp.net/threads/help-me-release-this-starblade-vc-arcade-translation.350059/