We now have irrefutable confirmation that AI was never planned for Make Your Mark. We already debunked the French VA who was found to have received false information from a fake Hasbro employee, but Hasbro themselves have dropped a rare response off and wiped out any possible rumors entirely with the twitter message above. I'll quote it here too:
The #MyLittlePony ‘Make Your Mark’ series has never used AI-generated audio or visuals at any stage of its production. We’re proud of our artists and actors who played a role in creating magical experiences that brought our characters to life and connected fans across the world. - Hasbo
I've asked for confirmation on Tell Your Tale season 2's dubs since people have been speculating that those are AI for weeks now, but on the Make Your Mark front at least, you can rest easy.