OP

Quoted from vid1900:

Nope, from that pic, I'm sure the HT will stick to it no problem, as is.
How the hell did the shop get orange peel over all the inserts too?? I could see a crater opening up along the insert edge , but across the entire surface seems odd.

Id just flatten the insert faces. Block sand the faces with 220, then 400, then wet 800, then wet 1000, then wet 1500 and finish with wet 2000. Buff with your 3M after that.
Dont over-sand and cut through the clear, just get it reasonably flat over the inserts.
(thinking more about this, if you want the practice, you **could** block sand the entire playfield flat and then buff it out. A lot of work, but you'd have the confidence to tackle any job after that...)