The profile is 2D only on purpose, 3D in Arx Libertatis only worked with the original alternate frame G3D OpenGL implementation in vorpX years ago, couldn’t make it work glitch free with the current proper single frame G3D implementation unfortunately. There are a handful or so profiles in the local profiles list that work in a similar fashion.
If you want to double check whether a game in the local profiles list is actually supposed to have 3D, use the supported games list.