I have a Rainbow BTA with mine rn.
I will say its tricky to feed the anemone without her robbing food from it, and that I got lucky the anemone liked the spot I placed it.
It is a legitimate concern the nem will make home in or around the burrow, the sting cells are brutal for a molting mantis and the mantis's activity will like kill the anemone (mainly them moving rubble over them all the time). I don't think they would ever try grabbing the nem, they're not loose enough once attached and they seem to do a really good job avoiding making physical contact with them.
bubble tips are less likely to move around so if you can get it to stay away from the burrow entrances you'll be fine, if you see it start moving, try to stop it from entering in or get rid of it if it keeps trying.