2 things :

• It's fairly new
• it's pretty complex

Let me explain a bit more :

• Since it's that new, I'm "afraid" that this won't last and would prefer something more future-proof, like LaTeX (won't implement it either, see point 2)

• Klevernotes is focus on Markdown, I like to add some small "extensions" here and there, but I would like to keep the general feeling of markdown, typst or LaTeX are both to different from markdown imo.

Note : I might implement KaTeX (would be useful for my math class lol) but I didn't made enough research about it to make it something certain

Edit : typst looks really cool and I might use it for personnal use, but not inside Klevernotes :-)