Is pooping when squatting healthier than on a train toilet?

No.: A baby won't be any healthier learning to pop while squatting vs on a training toilet. As long as the end result is that they get potty trained. Here in the us, there's a whole industry around "training products" - doesn't mean it's the only right way. Babies in other countries are "trained" in a multitude of different ways... And they do just fine.