[Quoth]

Most word processors not only get leading apostrophes wrong (like using ‘85 for “back in ’85”) but also use double closing quote and single closing quote on measurements like feet and inches or minutes and seconds (time or angular).
5’ 3” is wrong.
5' 3" is better.
5′ 3″ is correct. The Prime and Double Prime marks.
You can fake the marks by italic straight quotes: 5' 3".


Done in Georgia and larger so to show it.

Obviously if you embed a font and the ereader device or app supports it you can use the professional Prime marks (not related to Prime Numbers).

But if you don't embed a font or it's an old ereader? What happens if you you use real prime marks?

Should we always fake it with italics and straight quotes and then the fall back is " and ' rather than [] and [] or space?

No issue on paper. Use real prime marks. The " and ' are only for programming languages, in English. A throw back to typewriters as actually is the underline. IMO real ebooks and paper books should never use the underline except for URLs, they meant "typeset this in italic".