I was surfing the other day, got a hit on the Legacy of Kain wikia and remembered I had not fully completed these games but I wasn't really in the mood for these two's games annoying combat.

The first game I'm trying to use the debug menu to activate Invincibility or a trainer that offers the same thing but neither works, I can still be hit by enemies. Why?

Soul Reaver 2 keeps crashing. I found an old text file where I had found that said you should change a part of the registry, specifically the DisableVShader 0 to 1 but that didn't help, it even crashes on a low resolution as apparently it becomes even more stable on a higher resolution. Is this game just unstable? It's weird that the first game runs far better and at 1080p no less.

I'm running Windows 7 64-bit.

I can't say much about the trainer because I've never used it. I'm sure wrace could help. but he is rarely seen here (he is still posting on official Square-Enix forums and I think he still posts on Steam).

As for SR2. If it's random crashes during gameplay (sometimes preceded by sound corruption) then it's the affinity problem (the same as BO2 and Defiance). The details on how to deal with it are in the sticky thread.

I forgot to mention that I've created a bat file to solve the affinity problem with Soul Reaver 2. The problem is that it freezes and eventually ends up saying not responding right after I start a new game.

In that case I'm afraid I can't help you. I have never experienced that issue, and I played the game on 2 laptops with Win 7 64b.
Other than the generic advice (running as admin, compatibility modes etc.) I have two suggestions.
First - is simply running setup once and saving the settings. I know of at least one case where this helped.
The second suggestion may not solve the problem but it may help in eliminating some possible causes. Do you have an integrated graphics card and a dedicated one? If so, try running the game on the "other one" (this may not be possible on a laptop). On my newer laptop the game always runs with integrated Intel chip, but it's more than enough for this game (except some wind effect slow downs in Air Forge).