I need a bit of help with understanding how I should start making a text engine

I was trying to make a textbox engine for my RPG using Gamemaker Studio 2 as my game engine, and so far I have managed to make a pretty good-looking animation for when the textbox comes in and out. I think it looks really nice…

…However, I’ve come across some complications when it comes to the actual text itself… I have NO IDEA on where I should start with that…

You see, a basic rundown of what I wanted to do was keep the main lines of dialog on separate scripts (labeled as TEXT_EN and TEXT_JP, for the potential different languages), and have the dialog box object print the specific line from the TEXT scripts depending on which one I call, basically how UNDERTALE and DELTARUNE handled it (from what I could tell, they relied on arrays but that’s all I know, I’m not sure on how to utilize them to my advantage).

I’m not sure on how I should start doing that… And I tried following along with some guys on Youtube who were better at it, but it didn’t really feel right to me… I was planning on having different languages with my game, and these tutorials didn’t have that in mind… If any of you guys could point me in the right direction, I would GLADLY appreciate it. Thank you for your time.