If your software is so riddled with spelling and grammatical errors your customers cannot understand it, it’s not quality software, no matter how perfect the functionality is.
Same goes for any other non-functional requirement. If it’s too slow to use, it isn’t quality software. If it’s not secure, it’s not quality software. If it isn’t accessible, it’s not quality software.
Quality software isn’t just about producing functional software, it’s about producing usable software.
Besides, typo fixes are usually the quickest bugs to record and fix, and some more technically minded testers will be able to fix the issue themselves.