W212 2015 E63.

Am I able to just change these for the correct radius type and carry on or are my wheels knackered?

Can you post a pic of the lug seats on the wheels? I'd expect a raised burr where the cone seat contacted the radius seats. Best case, the correct bolts will re-form the seats; worst case the seats may need machining back to spec. My $.02

This is the only (terrible) picture I have at the moment. It seems like the deformation is only at the very inner edge.

You should be ok to just change to the correct ones. I see people in the import/domestic communities using the wrong lug nuts all the time.

Thanks. All changed now.