artefact
Just gonna point out that there are a number of instances of Star Wars spelling this specific word the American way, and I don’t think I’ve ever seen them use the British spelling of words in general: https://starwars.fandom.com/wiki/Sith_artifact
Looking at the sources it’s only written that way in books because the books are American published. The word never appears onscreen in-universe or in crawls. The only word that is spelt differently that does appear in the crawls is ‘armored’ in ANH and RotJ.
Eddie, I’d say stick with whichever you want. Imperials have pronounced Lee-a and ley-a, zed and zee, and lef-tenent, loo-tenent all interchangeable so it’s not unreasonable to assume their spelling is also varied.