The grey box problem had been solved with this commit:
https://github.com/Rinnegatamante/easyrpg-player-3ds/commit/215ed5b6c3a8fc11e0ab5740ff2e29cd188954af
Here's another test build updated to latest commit. Another thing that should be tested is romFs support since at the moment i have access only to a 4.5 fw console running nh 1.1b (and nh 1.1b doesn't have romfs support at all).
romfs should contain game files (like romfs:/Map0001.lmu).
Don't know if romfs file can be appended to a 3dsx directly or an elf file is needed. (The elf file is pretty big and currently i don't have a good internet connection <.<)
THis test build has a lot of fixes, new adds and improved framerate.
I hope someone will report bugs like
@pdapanda did.