buffer-overrun

It sounds like you're really figuring this thing out! And, I think you're right on the mark with the distinction between triggers and squicks, and how they work in this setting. Having to slap a warning on part of my life experience because someone finds it icky would distress hell out of me. This might be something really good and useful to talk with your group about -- the idea that saying, "Writing about X is just nasty," or "I don't want to hear about X because it grosses me out," is the opposite of helpful, but saying, "I'm not sure that this way of describing X is getting it across in the way that you want," is constructive. And, it might not be a bad idea to talk with them about what a trigger actually is. I don't know about real life, but online it surely does seem that quite a lot of people think it's just an all-purpose word for any negative response to anything a person sees that they don't like.