Hard to tell honestly. So far there was always some surprisingly straight forward solution If had any problems with the math engine. There is actually a lot of public research how equations can be solved/simplified with computer algorithms. So I'm optimistic. I also stumbled upon a few cases where Mathematica itself didn't quite do things correctly itself (rounding errors, missing simplifications, etc.). So maybe it's actually a little overhyped …

I also found problems with integrating some obscure functions a few years black, though IIRC the issue was remedies by using the amazing Rubi package:

https://rulebasedintegration.org/