The written reasons have been released here, filed under "Yann Sonngo'o". To summarise:
Songo'o apologised during the game and admitted the charge on the 22nd February. He said English was not his first language so he did not appreciate the offence he would cause.
The provocation alluded to seems to be that a player leaned in and when Songo'o asked why, the player said he was "going to kiss him on the lips". There's no reference to racial abuse or any other kind of insult/abuse aimed at Songo'o.
To be honest, I'm still pretty disappointed in the club. When provocation was alluded to by Derek it sounded like something much more severe than was released there, unless there's something more that wasn't mentioned for some reason. There's absolutely no way a homophobic slur is an appropriate response to being told you'd be kissed. If Songo'o admitted it and apologised immediately, I can't understand why the club couldn't issue a public apology as part of their statement. I can accept Songo'o's apology and at the time he didn't understand the offence due to English not being his first language, but after it happened the club could have avoided a lot of bad press by issuing an immediate apology.
Ultimately he's apologised and we all move on, but I hope the club has learned from this situation.