T 14-
I'm not at all sure how one "bumps" a T 14 safety, it is no where close to the hand or fingers when firing or holding? If it moves easily, then it is not correct and needs fixing. Just FYI, it also blocks movement of the very long sear bar, so it is a pretty "good" safety and it requires a highly intentional movement to change its position from safe to fire
Interarms-
That is a really strange problem, but like I said weeks ago- every Interarms or other luger copy I have seen has problems! Of course people don't bring it the good ones or the ones they don't fire with a problem!
It must fit really loose and have no or an undersize retention spring, but still should reset it self as kurusu says.
Last one I fired would set the safety toward "on" with nearly every shot, just enough for the safety bar to rise enough for the sear bar not to move out. No amount of tweaking would fix it and the owner did not want to spring for a vintage, original forged safety. The ones furnished are cast and have little or no "spring" to keep them in position.