I am a FFXIV gamer and I depend a whole lot on ACT's custom trigger TTS to enjoy the game because there are too many visible information to digest in the combat contents.
One of them is boss' spell casting and this can be detected easily in ACT, however there are a lot of gimmicks that do not involve casting and in those cases, instead of logging a single 'Boss starts casting xxx', multiple specific messages are logged, each to the group member before the actual action occur. Using those messages as trigger will give you a noisy situation since multiple TTS will be ringing simultaneously.
So, how about adding a Cool Down option to each trigger? If cool down is set and it is triggered recently, the trigger would be in sleep mode until the cool down is over. This can be useful in many other situations.