Q: were the carbon steerers supported internally by a glued aluminum insert? or just a compression plug? or just a star insert?

I checked this on my Wolf SL fork with OS-115 stem, no visible deformation. The AlphaQ steerer has a inner ally sleeve that is 30mm deep, and it's designed to reinforce the stem clamp area of the CF steerer tube.

FSA compressors need to be carefully installed in insure the compressor bands line up with the stem clamps, if they don't, it's worse than no compressor because they will push out above or below where the stem clamp will push in.

This may be a steerer tube headcap issue rather than a stem clamp issue. Check this before knee-jerking and throwing out your OS-115s or RD-120s.
I've seen many butchered Cf steerers that were cut incorrectly, leading to strands peeling back, and do-it-yerselfer-ebayers with the wrong headcaps, designed for metal steerers.