The developers published an update with new languages options so I was excited cause that way my nephew would finally understand the dialogs in the game -he can only speak Spanish. However, I tried to change the language from the in-game options and the GOG Galaxy options for the game, but I can't click on the option for some reason -I just added a screenshot with it.. Do you have any idea how to fix this?

How about the ingame menu? With the newest update applied there should be the item "Language".

It only shows English.

Ahhh OK.
You can switch through the languages sidewards with arrow keys or controller ;)

...Oh. It was that simple, huh? I feel so dumb.

Thanks a lot!