>> How often does it poll the account for changes for calendar events? Is it synced with the mail checks (EWS)?
Syncs on every mail check, yes.
Also when / if you make changes with a Calendar app (Google's own, or any other), then Android will "tell" AquaMail to sync those changes a few seconds later.
>> It was me and I can't believe how fast you fixed this!
Thanks to your great debug log, as it was something I'd never see in my Office 365 account (it was quite a serious bug).