Ok, i know it's been a long time ago, but there's a bit more progress.
Bigchillghost updated his convertor which can now extract the models from the rendermesh.nx files, a big thanks to him.
Rendermesh.nx files uses 64-bit integers for certain offset fields while the other one from the PC version uses 32-bit integers, which explain why i got nothing interesting whil using the old convertor. Shakotay2 and DKDave also helped me for these, a big thanks to them as well.
Here's a picture of several models i extracted from the files with textures applied :
Unfortunately, we didn't go further.
I found where the rest of the materials (skeleton data, morphing data, file paths, etc...), which are located in the level files.
There is block3000000000001.block.nx, probably used to morph models, and it mention other things.
vt_index.bin.nx mentions a lot of textures name.
And rendershape.bin.nx mentions also textures name as well as models name. I also noticed it's contained bone names, which suggest it may contain skeleton datas.
Also levela-3 contains a lot of xml files, which mention a lot of things, but i don't know what they are meant to be used for. I'm not even sure if it's connected to the other levels as well or just only the level where they are.
I sended the files to the guys, but then they stopped answering, except Shakotay2 which explained a bit about a xml file. He have a bit analised a block.nx file, which it contains models identical to the rendermesh files, but with detached polygons and no UV maps.
Sorry for the bump, but i'm really out of ideas now. I tried insisting a bit, but still no answers. Maybe we could discuss about this here and try to achieve the goal.
Here's the thread by the way :
https://forum.xentax.com/viewtopic.php?f=16&t=23150