Seller paying for structural engineer - removal of internal wall

The seller has agreed to pay for a structural engineer to inspect the works he did in 2022 when he removed an internal wall between the kitchen and lounge to make it all open plan. We need official confirmation and documentation that it was non load bearing for when we come to sell it in future as we know we will be asked.

The seller is a tradesman and is confident that it was a non load bearing stud wall and that the works will satisfy a structural engineer. He has provided photos which we have sent on to a structural engineer who has said it likely was non load bearing (but of course requires an in person inspection).

I wondered if there’s anything else we need to do if the above comes back fine? Would he still have needed building regs and permission? What about things like fire safety?

Thank you