> Typst authors being germans, one can hardly accuse them in the "everyone uses English" attitude.

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.