Given my having read this series three times through since it was last on catch up...yes, I enjoy it very much.
The author has done some things that I'm pretty sure became a headache for those doing the translation, the most "fun" of which, in my perspective, would be handling how those from Sym interact with others.
They're, um, reticent?
They conceal their emotions.
This is reflected in their non-expressive demeaner.
It also, I'm thinking, ties in with their speech.
The pauses, indicated by a comma practically every other word? (Which has to be a bother to the translation team, they aren't doing this for a lark.)
I don't think that's entirely unfamiliarity with the language of Selva. They may well be seeking out phrasing that conceals emotion on the fly. Making sure their word choice conceals their emotions while still conveying the desired information becomes more difficult in a language developed by folks who don't habitually conceal their emotions. Understanding what phrasings would reveal their emotions and which wouldn't, well, that's a tricky thing?
Compare it to grasping "noble speech" in Bookworm and the Dahliaverse.
They'd be more fluent if they dwelt entirely in Selva, but since they spend half the year in Sym and the other half trading in three foreign cultures, and pretty much keeping to themselves outside of trade negotiations...negotiations which can be handled by specified individuals.
And it isn't like they went to school to learn these languages. They pick them up as they travel.
The next major headache would be the foodstuffs.
Some might argue I've got these out of order in regard to which is the most bother for the translators...which may be the case.
Foodstuffs happen all the way through, dealing with those from Sym less so.
Anyway, keeping the terminology straight, keeping in mind the physical characteristics of everything?
They have to have a glossary they're referencing.