Speaking of categories, I just tried:
- Sending an invite from Google Calendar (web) to Office 365 (web), assigning a category in Office 365 (web), then checking mail in AquaMail
- Creating a new event in Office 365 (web) with a category, refreshing the calendar in Android (handled by AquaMail)
- Clearing categories on the second event, assigning a new one, refreshing the calendar in Android (handled by AquaMail)
- Updating the invite (first event) in Google Calendar (web) with a new "start time" and "duration", causing an automatic "event updated" message to go to Office 365 (web), then refreshing the calendar in Android (handled by AquaMail)
The category (color label) and the times were propagated through just fine, from Office 365 by AquaMail into Calendar on the Android device.
My time zone is Moscow, Russia (+0300), so the code had to handle a "non-UTC" time zone conversion too.
So yeah, it's a "works for me", would need a clarification.