My exact thoughts, the playfield should be MINT if no stuff ups occur. The decals are original so if what you're saying is right, they should be fine???

When you said "if done correctly", what do you mean? Is there a right way and by the sounds of it a wrong way which no doubt will send tears to my eyes. I know if I don't ask I'll 100% do it the wrong way

Nino or one of the other guys should be a able to confirm this if I'm right..
Either way, mylar removal should be done very slowly and carefully, either by the freeze method or heat gun.  I've only done it with the heat gun and had no major problems, although I wont do either on my Police Force for fear of removing decals.  But also I'm not doing it as it doesn't need it.

Post a couple of pics to help.  Is it full pf mylar or only around pop bumpers and slings?