Good SF would used something universal, like an Angstrom.
"How tall was the attacker?"
"Hmmm, maybe 1,750,000,000,000 Angrtroms?"
Sci-fi and fantasy story telling is quite odd in a way.
For convenience characters generally have a "common" language. But what language is the book that the reader is reading written in???
Is the book a translation from some mysterious fantasy (or future) language to the language of the reader?
Is the "common" language meant to be literally the language that the reader reads?
In the Star Trek future everyone speaks the 20th Century American dialect of English. -- Then maybe use 20th century American measures.
In the fantasy of Lord of the Rings, the common language appears to be mid-20th century British English. -- Then maybe use 20th century English measures.
But if instead the "common" language is really a different language altogether and that language is being translated into the language that the reader of the book reads, then translate measures to the modern language along with all other words. Why single out units of measure for NOT being translated into the language the reader of the book reads?
In conclusion, there is nothing wrong with using modern units of measure in your fantasy/sci-fi books. And potentially a lot wrong with singling out units of measure for the category of made-up terms to sprinkle throughout the story.