This is AFF, we love stories around here, especially if there’s stripping involved
In the Potter fanfics that I did write, I’d switch a bit too often, IMO, between 1st and 3rd. Since then, I’ve kinda formed my own rules. I’ll avoid 1st because there’s a lot of “I’s” not to mention it’s tougher to remember the main character’s name. When I started SR, I did a utterly detached, third person, no-mind-reading, but I’ve come to let a bit slip in if it saves a lot of awkward exposition/dialogue, or as a hint to the reader (ie, “lied” or “changed subject”) so they know there’s something off. I think it came down to .. I want the narrator to be truthful, always truthful, but the characters can lie and get it wrong
So, which dialect of Klingon are you’re looking for? A google search claims there’s at least eighty.
If the author is really wanting to show their bilinguistic skills, there’s no reason they can’t have English subtitles when it’s meant to be understood.