Four of the keywords you've listed are most definitely used:
[texchanges] is used in the default buses that have rollblinds - it's used for the number blinds that are made up of a series of textures that are changed by a float variable.
[detail_factor] is used in a number of default sceneryobjects - it multiplies the object's screen height to change how far away the object is visible from.
[texcoordtransX] isn't used in any default content, but [texcoordtransY] is. They translate UV coordinates in the U and V axes respectively.
[particle_emitter] is used in the default fireworks cubes for the fireworks particles.
These two I've not seen before, but are present in default content. Whether they actually do something is not guaranteed.
[noDistanceCheck] is used in the default B727 plane and Mi8MT helicopter, presumably to keep them visible from further away.
[matl_zBias] is present in one default sceneryobject, but commented out. Looks like it might adjust the relative position in the render order, if it's still implemented.
The other keywords are not used in any default content, so whether they are implemented or not is unknown. I would also add that [dir] and [friendlyname_inv] are both present in default OMSI 2 content, but I can't seem to find any function to them.