I wouldn't worry too much. If they stay away, then they aren't coventry city anymore, if they come back, attendances will rise (as some will forgivee and forget - very short memories some people), or they will arrange yet another fudge with the FL, claiming because they are playing in a temporary stadium they will have temporary exemption from the FFP rules!
Once the FL broke one of their rules they were compelled to break each and every other rule otherwise they could never justify breaking the rule on location! Can imagine other clubs are going to raise a stink about cov sooner or later (a few clubs are going to be pissed they only got 10 points!)