[1] https://www.etsy.com/listing/1099735271/the-codex-a-zine-abo...
[2] https://i.etsystatic.com/9756188/r/il/09766b/3387078510/il_1...
It's not just super-flexible in the output but also in the input. It takes one short line in your preamble to define a new command or math operator, redefining long commands you use often - with parameters and/or optional parameters, if you like - to be whatever you want them to be. It sounds like you don't know that. Everything is redefinable, and it's easy enough to also make a short command name for a combination of symbols, or a new symbol, or anything you like. Commands can even draw pictures inline, e.g. with TikZ.
What kind of shorthand do you use with your script? I honestly find latex's shorthand already short.
These days my notes are all Markdown with inline LaTeX for math. I haven't yet found an editor that support "global" LaTeX macros/shorthand. Things like matrices can be bit of a pain, but then I haven't written any since linear algebra.
https://vedthiru.com/tools/notetaker
Disclaimer: I wrote it.