As mentioned above, no. Things are going to continue changing constantly with every version, so I'm not intending to chase down compatibility bugs until everything is more complete. The bug that was causing crashes on more accurate platforms and hardware was fixed in my tooling a while ago, but I have no idea whether the mod currently works on hardware or not as I have no practical way to test it frequently nor any inclination to.
Menu backgrounds are made up of dozens or even hundreds of tiny tiles, which each use either a 16-colour palette or a single solid colour, with a limit of only 16 discrete palettes per menu. The format is known well enough to dump menu images in a non-editable way, but the difficult part is finding a practical way to both make them easily editable and avoid making it extremely easy to break them so that they're no longer importable.
I managed to hex edit the Vauxhall dealership onto the North City menu, however the tiles and palettes for that area of the menu already existed and I was mainly copying them over (and merging palettes to make space for it). That edit still took a full week of work however, making menus impractical to edit until I figure out a good format to convert them into for editing.
Car models aren't fully understood - the reflection data is a mystery, and without knowing how that works it's impossible to create new faces / polygons on a model unless they're matte and non-reflective. Again, the model format is known enough to hex edit minor things to fix texture mapping or move vertices, but any major work is again impractical without a tool to convert to and from a common format that can be opened with tools like Blender or 3DS Max.
The race music is editable, but the length of each track appears to be hardcoded into the game, so unless you want to use music that's identical in length to the originals, you end up with gaps or tracks starting and ending halfway through. Fortunately there are no music bugs to fix, so I'm not looking into this at all.
Track models are also more or less an unknown - there are very few track bugs so I've not investigated this at all either.
The Arcade mode car stats are also a mystery, I don't even know where they're stored never mind how to edit them. The same applies for the manufacturer data that blocks BMW cars from having aftermarket wheels fitted in GT mode, which may be hardcoded.
The savegame format is only very vaguely known - this wouldn't normally be an issue, however the 'attract mode' replays that play when the game is left idle at the main menu are actually a replay savegame, and broken in the same way as any other save.
That particular bug is likely fixed for the next version, but that's not a guarantee that there are no other incompatibilities.
