Yes, I agree that all prims (no matter which geometrical ones, typefaces, or logos) should be CC0 without exceptions.
If an author want to claim copyright under CC-BY 4.0 for some works (supposedly logo etc.), they should be submitted in subparts folder with appropriate comments, I think.
If an author want to claim copyright under CC-BY 4.0 for some works (supposedly logo etc.), they should be submitted in subparts folder with appropriate comments, I think.