Using opening balance items is a totally legitimate way of brining in open AR, accounting approved, expert approved. It does depend what you are doing though, so yes make sure you are not doing anything in isolation.

Bringing in historical transactions and inventory movement increases the complexity a lot. In my experience accounting usually doesn't care so much about this, usually it is sales/purchasing/warehousing that care more.

Experts can be incredibly helpful and letting you know best practice, telling you the implications of the choices you want to make, giving you examples that other clients have done, etc. That being said, the worst mistakes I have had to clean up have been experts making decisions when they THOUGHT they understood your need. You really shouldn't do something just because an expert says "do it this way". Have a conversation make sure everyone is on the same page about the needs and the implications of the possible ways of doing things.