Why would a user who types only in English prefer a system that was optimized for all languages?
Things like "if you ever want to translate your document from English to XXX, you will also need to port it from Typst to LaTeX" tend to be dealbreakers.
On the other hand, one can easily understand why, bein German, they assume Figure, Equation, etc. will always be capitalized.
> Typst `dif` math operator (as in dx/dt) produces upright 'd', quite unexpected to ones used to slanted 'd' tradition.
I would indeed expect an upright 'd'. It's an operator, not a variable. I don't recognize the tradition you're mentioning.
That's strange. I've never seen a math article in English with upright 'd' differential, only have seen it in German and Spanich articles. It's also math italic in TeX (you can check Knuth's TeXbook).