I've been trying to put ReShade+SweetFX working with S4League, but I don't know what is happening, the game gets shutdown while ReShade is doing its work.
Here is the log file, it's traced, I just changed the name back to look at it. (as if i understand anything in it >.>)

I don't know if you can test with the original game(from AeriaGames), but I dislike that one, so I'm playing on a private server. If you want their webpage let me know.
I thought the problem was from the game and its hack shields, so I contacted the owner of the server first.
Ticket I sent to them. (if you wanna read it.)

And I'm sending him the link of this post, so he can follow it. (if he wants)

I don't know which sort of cheat protections the game has, but I do know that at least the client side "HackShield" from AhnLab doesn't work with ReShade, I'm guessing a few others as well.

Just a quick note: S4 League changed the cheat protection service, now it is "XignCode". ReShade + SweetFX is now working.