Firstly, thanks for picking CY up. I see a good addon incoming :)
In castyeller, there was a functionality to announce the reason when a spell fails to cast. I checked the option "Spell failures" but it won't announce when i try to cast it while the ability is on cooldown or my target is out of range / dead, etc...
Also the whisper announce whispers something like "Cast MySpell on PlayerName( )". I think whisper could be better if it's simpler. "Cast MySpell on you!" the word "you" is better than the whole character name when you are whispering that person.
It would also be a nice option if chat outputs could be configurable. what i mean is, if it was possible to announce one ability on "/say" another one only in healers channel and some other ability to be a "/yell". It's global at this time and when i select those, abilities are broadcast to every single one of them.
Hope to see the failure announces soon. GL with the development.