I have read the full report on the FA website, it is utterly damning of Casilla but for me the fact that Leeds use Tyler Roberts via a WhatsApp message to suggest to Leko that he misheard is a particularly low point of this sordid episode particularly in the light of the fact that at no point at the hearing did Casilla deny he had used the phrase reported. Overall I think the Casilla is very fortunate to escape with an 8 game ban.
As for the PFA, Kick it out etc... well it's par for the course sadly.
http://www.thefa.com/news/2020/mar/03/kiko-casilla-written-reasons-030320The hearing PDF file is at the end of the linked website page.
Casilla repeatedly denies use of the phrase, contrary to Standaman's comment.
He claimed to not know what he was supposed to have said, even when it was clear that all the Leeds players had discussed the exact wording of the insult on the coach immediately after the game.
To his shame he used the 'I don't speak English' defence, amongst other lies.
Leko was commended by the Independent Regulatory Commission for bringing the complaint and his conduct throughout, which given the use of QC's to cross examine him must have been tough for a young player.
It is a good job that he had a strong, credible witness to the slur in M Bonne to corroborate his claim.
Having read all of the evidence, and the pressure he must have been under, Leko has gone up in my estimation.