I'm sure it's been said by another poster, but the most hilarious (and desperate) part of this whole saga is the Cardiff claim that this allowed Palace to achieve an
'unexpected' 3-0 win.

Against that rabble? We under-achieved, should have been 6-0.

Complete rubbish, Palace make the same contributions towards their partition in the Premier League, they will get same treatment as any other club.

As stated before: SECTION B Rule B15 states: "In all matters and transactions relating to the league each club shall behave towards each other club and the league with the utmost good faith".

SECTION B Rule 17 goes on, "A Club shall not without the Board’s prior written consent either during its membership of the League or at any time after its membership has terminated disclose or divulge either directly or indirectly to any Person whatsoever or otherwise make use of any confidential information as to the business or finances of the League or any other Club or any of their dealings, transactions or affairs or as to any other matters which may come to its knowledge by reason
of its membership save to statutory and regulatory authorities or as may be required by law or to such Officials and Auditors of that Club to whom such disclosure is strictly necessary for the purpose of their duties and then only to the extent so necessary".
That to me is what Cardiff may be using as justification for their complaint, I may be wrong but as I read that as a non Englishman, it could also implicate Cardiff for their failings.

Also there is no mention of this type of issue in APPENDIX 5 & 6 Managers and clubs code of conduct.

So unless the Premier league introduce a new rule, it's a storm in a teacup, as this sort of thing has been going on for years, even when I was playing it was going on, every club tried to get their opponents lineup before they named theirs, and I retired in 1977, it's called trying to outwit your opponent.