Okay, so, uh... I knew this old code would be rough around the edges but, not only did I underestimate just how messy it'd be, I also failed to consider that this was a project made on an operating system I am no longer using, in an outdated version of Godot, and it uses tons of deprecated features that I can't easily migrate with. It'd need to be updated to the latest version, and with all the bugs I want to fix and even just minor stuff I want to add, it'd be way better if I simply started the entire Godot project from scratch.
For now, though, I need to focus on Dreamscape and get that finished. At the very least, there's not really much demand for it, so I can take my time. This might end up getting put off for years, if I even get around to it at all ;-;
Again: it's like your first factory in Factorio...