Having had a bit of time to reflect, I really don't think Palace have operated in any way in breach of UEFA's rules. Interpretation of Rules can be "absolute", "in the spirit of", or "brown envelope time"
What this situation has demonstrated to me, is yet another Governing Body , who is not fit for purpose.
The blame for this whole farce should be placed firmly at UEFA's feet, and not put on any club or owner.
UEFA sat on their fat @r5es, quaffing wine and delicacies all over the world, whilst their rules were not fit for purpose. Any kind of legal challenge by any club at this stage, might bring in to the open how badly UEFA have operated.
This theory in no way assists Palace, or any of the clubs under scrutiny. I think it will show how carefully UEFA have to tread with their decisions, or some club's legal team might want to tear UEFA a new one, and bring them all down.