I don't know much about how Godot handles text, Strive handles text in many different ways with no simple way to access all text. Most of the files can be opened and changed with a decent text editor. Though I would recommend having a decent ability to read programs before attempting a large project.
The default text for the initially defined GUI is stored in .tscn and .scn files. Stuff like buttons and labels almost never change, but rich text boxes are often updated by the code during the game.
The code is stored in .gd files and is a bit messy. Some text is stored as simple constant strings and some text is created by adding together or replacing many strings. There are at least 2 systems for dynamically creating text from either person data or selecting one of the random choices of text within a string.
There is a case where someone worked really hard to translate the game(https://itch.io/t/498107/is-there-a-suitable-scheme-for-translating-game) not sure where it is available though.
Strive 2 is being created with planned accessibility and should be significantly easier to work on.
