I played PSO2 to its fullest on the Arkslayer translation patched version and had a blast. I missed out on some scenes due to it not being translated on parts, but I remember scenes and such pretty well. Two things i know changed:
1: Bath scene. Blah blah pervert whining. I actually found the scene funny and any scene with Phaleg is awesome. (That ending part was hilarious, I recommend looking for it on YouTube.)
2: A curious dialogue option for your interaction whit Margereta after the Apprentice fight telling you to "Get in her face" instead of "Kiss her" which could have been a translation error on Arkslayer side since I can't read the original Japanese text. Can someone confirm?
Anyways, anything else changed? I recall a reddit thread making a post of multiple changes.