[Freeze]

I have a stock TM G19, well almost stock, now with an enhanced recoil spring in fact, so my problem would be worse than yours.

TM G19 uses the same 15mm Cylinder system as the HK45 / USP9 / P226E2 / Gen 4 G17 according to what I've read/used. (Own/owned all but the Gen 4 so far)

I have in fact noticed that the metal slide catch does eat at the plastic slide / the metal piece inside, however, I have not deemed this to be a major issue. It still functions as normal and even if the slide catch stops working, at the end of the day it'll spit out all the bbs in the mag and I'll just be dry firing for a couple shots before I realize it. (Had this happen to my old Gen 3 TM Glocks too lol)

TL;DR: I have the same problem, I just don't do anything about it because at the end of the day I don't deem it to be a major problem.