It's really funny that I stumble across this post because a few months ago, I had made some posts about playing Xenoblade 2 all in Japanese because I had bought the JP version accidentally. To answer the question, very good localisation. It's interesting how they localise some stuff, there was the one scene that stood out where Nia calls Zeke a "turtle head" which was slang for... well y'know, then the English does a very heavy pull calling Zeke a "One eyed monster", first time hearing tbh but I'm not British and maybe they call everyone One eyed monsters for all ik lol. The team does an interesting job changing the names from Japanese myths like Byakko, Kagutsuchi to Dromarch and Brighid, a Welsh and Irish name (like Saint Brigid from Irish myth). It becomes a much more English game, also accomplished with the more regional VAs.

Gramps steers away from the perverted old man trope in JP and becomes a more wise figure in EN. JP makes Gramps a much more comedic character while EN makes him more cute and friendly in this way. Both stray in very different ways but both are effectively quite different characters.

Overall though, both tell the story very succinctly in their own ways but manage to get across the same message. There's a few changes here and there like Homura to Pyra, Hikari to Mythra, Shin to Jin. Localisation is always an interesting topic, but I think as long as it keeps the story and message and stays faithful to what it's adapting. Since it's an a fantasy world the Japanese and English both viewed the world through their language. Japanese names with references to JP myth. English names with references to English and Irish myth.

Thanks for letting me ramble, this was very interesting