When using anchor-based positioning, the anchors seem to be in the right place:
T Anchors
commaaccentcombo Anchors
However, the alignment is far from what I would expect.
Expected Position
lowercase tcommaaccent
The lowercase is just what I would expect.
I was missing the bottom anchor on the T as it was not visible when zoomed in close.
That is used for attaching the commaaccentcomb. Still, the default anchor positions for the italic T are far from ideal.
This bug affects more than just this character. It will be fixed with the next upcoming update.