no, jcl has no plans to add more uv-sets to the model format. it would make the model format more complicated and i think it's jcl opinion that light mapping doesn't make sense for models since they are more meant for moving them around per script and being animated. i think light maps for models can make sense even once a7 level geometry is better supported (map compiler, fbx import,...). for example because models can have lod.

gamestudio's vertex format kind of supports 4 uv-sets. there are 3 uv-sets. one actually is meant for the tangent but it consists of 4 floats which also could store 2 uv-pairs if you don't need the tangent.