Yeah… I’m not super aware of the specifics, but expanding the class list is a more advanced endeavor than I’m qualified to offer any real advice on.
I’d recommend asking in the #gba_coding_help channel in the FEU Discord if you’re super serious about expanding the class list. That’s where many of the community’s brightest coding aficionados hang out and discuss their work; folks there will definitely be far more qualified than I am to help you with this.