I give fair warn first that experience depend on which server player plan to join, not every JP player is OK with English speaker.
As I type before in other thread, is not because of racism but sometime because do not know much English. Communicate become very difficult sometime unless you know some hira or kata to give idea. In some case will be needed to talk to others? Then become problem if you can not understand dialect.
You can try ping all JP server and find where not much lag problem?
I reply for information only. Kujata is Elemental Data Center with Tonberry which is wide known as community with both English speaker and JP speaker so communication most of time is easier.
Most should be able to speak EN and JP if join Content Finder group.
Activity and community is because there no point in boycott PVP or complain and say do not want to play PVP. Many PVP for fun or to grind level? But usually do with mindset to try win while do so.
I would not say JP excel at MMO in same way most NA people understand word "excel". Both player culturally different, maybe play for different reason? or at least play game at different level of intensity?
Can be many reason.
On data center I play on, many time player have been kick from PVP game randomly and no word exchange. This problem have been occur many time since vote kick issue into PVP and is not only kick English speaker but also JP player. On outside website of SqE forum, is mention they remove people for many reason which both childish and sometime silly.
If most really want transfer server then: If this happen to you, I advise you take note some name in party then report to SqE harassment.
Other than that if remain respectful then will be no problem, as I have had NA player in party before but always say thing to be negative and he dismissed from party not too long after.
I hope you enjoy life on new server~