If they can’t “see”, then how would they ever travel intergalacticly? Seriously, they’ve have some form of sight sense, even if it’s braille.

And the point is that math is indeed universal. The ratio of a triangle will never change. And again, if you’re a space fairing civilization,you’d have figured out triangles. You’re confusing differences in culture with basic rules of the universe. It’d be like saying “what if they don’t know what gravity is?” like they just somehow float around because they’re ignorant of the laws of gravity.