I put some Mylar over an area where I had some key line insert damage thinking that would be enough. But the insert kept raising and eventually air bubbles started to form around the inserts and looked terrible. So if you are able to, flatten the inserts and glue them back in place from underneath before Mylar. I had to learn the hard way.
Forceflow mentioned a playfield protector. I put one on my T2 and it will smooth out any playfield damage you may notice with the ball. But it will change the way the ball plays and some don’t like that. I think the ball gets more traction on the protector and reduces the speed of the game. The protector does its job well and looks great, but my T2 doesn’t play as well as it used to so ultimately a clear coat will be in its future.