I had a guy weld the flash hider/extension to my vz-58 barrel and he welded over the USA markings on the thing. I tried to file some of the weld away to see if it would show again. No luck. Can I still count it as one of my parts or do I have to get something else like magazine floorplates or followers to get the correct parts count?
Chances are you will never be asked. Plus Theoretically in this country we're all innocent until proven guilty. A receipt also works well. Also there are not too many foreign devices even available for these.
the list czusa has published about the tgi rifles states imported parts as
4 bolt carrier
5 gas piston
6 pistol grip
9 magazine body
10 muzzle extension