Can I just add the new line in the lua/moon files related to the character (in the dialogues folder) and then add it to the translated lua or is it more complicated than that?

Thank you very much! I also figured I needed to add the English line to the text_english.lua file in the main folder (otherwise the game would freeze). In case anyone else wanted to know the steps:

1. Find the last dialogue ID, which is the number in square brackets in the text_translated.lua file. In this case the last one is t[653], so any new lines of dialogue should be 654 or higher.
2. Unzip game.zip in a separate folder (so you don't mix up files) and open the dialogue folder. Open the files belonging to the character (unless it's Ines, I guess, in which case you'll problably need to find the exact spot/file depending on the dialogue).
3. Add your new line in both XXX.lua and XXX.moon by following the same syntaxt. For example:
   say(ines, INES(654, "This is a new line of text!."))
4. Remember to create a new game.zip (containing all files and folders directly, there should be no "game" folder) that contains the edited files and place it in the main folder.
5. Add your line in both text_english.lua and text_translated.lua in the main folder. For example:
   t[654] = "This is a new line of text!" -- comment with the speaker and the folder/file you can find the line in, if you want

 Any step you miss or do incorrectly will break the game so be careful!