NCGR and NCER files with custom headers

I am part of a translation team translating Tingle's Balloon Trip of Love. The games graphics are stored in what I'm 99% sure are simply .ncgr and .ncer files with a custom header. These files contain "GCV" and "ECV" in their headers, so I guess they would be considered .vcg and .vce files (little endian, right?).
All the graphics in the game are LZ77 compressed and stored in huge archive files, but for each archive file there is a .inf file that tells where each file starts, allowing for...

NCGR and NCER files with custom headers