I don't know how to add diacritic in Deadpool The Video Game?

I will add that the game was made on the engine: Unreal Engine 3 :confused:

Could you provide some more details on what exactly you are attempting to do?

I would like to translate the game into Polish.
I translated almost all the dialogues, but I can’t add to the game Polish characters: A, C, E, L, N, O, S, Z, Z.

It better is you ask about this in the UDK (UE3) subforum:

Or talk to the developers, you can’t edit built games using UDK or the UE4 editor. These forums are for games built from scratch rather than editing commercial games.