Hi,
I wonder, is there still a bug?
tcaron is composed from t + caron.alt - and thats ok, but the anchor i think it should be top right. Now its linked to bottom. Or maybe I don’t understand something?
What anchors do you have in caron.alt?
Hi, actually its caroncomb.alt (i created it myself) and added “_topright” anchor manually.
I have some problems with duplicating diacritics (caron.alt vs caroncomb.alt) I made 2 of them - wasnt sure which one will be used - now i see its caroncomb.alt … Combs and legacy diacritiics could be more clear… but this is another topic.
So, the anchors are:
_bottom
_topright
Actually I now deleted bottom anchor and now its working! So i think thats was it, but dont remember that I made bottom anchor in caron.alt / caroncomb.alt…
Anyway that was helpfull 
caroncomb.alt has _topright by default. You can reset the default anchors with Cmd-Opt-U.