It’s true that the concept of ‘universality’ wouldn’t be expressed using a word like uchu — perhaps more likely something like fuhenteki (普遍的) or just fuhen ? —

It’s true that the concept of ‘universality’ wouldn’t be expressed using a word like uchu — perhaps more likely something like fuhenteki (普遍的) or just fuhen ? — but this is how one Japanese dictionary chooses to define uchu: あらゆる存在物を包容する無限の空間と時間の広がり。 So it (if you trust this definition) refers to time as well as space. It’s slightly more abstract than just ‘space’. The Japanese entry corresponding to the English Wikipedia entry for ‘universe’ is also called 宇宙, though it is of course effectively about space. …considering it further, I think you’re completely right. I’ll leave what I’ve written above in case it’s of interest to others.