I have a more complicated system in mind to improve on this and make it work better with the (text) dialogue, but it'll probably have to wait for a later update. Right now it can choose what expression to show and how long to show it based on the current situation, and reacts appropriately when the mouth is full. The improved version will allow me to add super-specific rules for when certain dialogue/expressions are shown, so I can add special cases in the dialogue files (like if AJ and Big Mac happen to end up together, etc) without needing any code.
Working on the cum fluid renderer some more- it now renders way more efficiently, and I'm hoping to fix up the shader a bit tomorrow so that the white fluid shows up against Rarity's white coat. >.<
I want to cobble together a release for everyone to play with the Rarity rig, but it'll be in a pretty rough state for now. The full "Rarity update" will include a nice character menu, better UI, and a fuller set of animations for Rarity. That'll take a little while, so hopefully I can push out a few development builds before that to show off what we've been doing.
And remember to come hang out on the streams and make sure I'm still working! :3