This is strange. I have all DLC too, and never encounter such a problem in my game (My game only created 5-10 new townies per week, and they are all normal townies, although I have over 400 sims in my starting save so maybe this help too).
I can’t help you with it but maybe you could try bienchens mod less fame (Expansion Pack -> Get Famous -> townieoverhaul_lessfame -> nonewaliens.package) You could try her other modules too, maybe it help with the townie creation.
I use only her alien module + barfly. It always worked for me without issue, and I never got new aliens (I only allow 10 aliens in my game, because I think they should be rare!)
