Probably shouldn't have to keep checking what syncs and doesn't with iCloud Music Library.
Looks like Plays and Last Played Dates are still an issue. If I play a track on my iMac, the Plays and Last Played date update as expected. The same track on my MacBook Pro does not increment. If I play a track on my iPhone, the tracks on the iMac and the MBP increment Plays and Last Played correctly. Played from an iPad mini, nothing updates.
Playing tracks through Home Sharing works as expected.
This mishigas seems to be what is happening for others.