Luna Display - multiuser problems

I’m using Luna display in Mac-to-Mac mode. My primary machine is a 2020 27” iMac - this has the Luna Display usb C dongle fitted and runs the Luna Display app. The secondary machine is a late 2011 27” iMac, running the Luna Secondary app.
I have the machines connected via a thunderbolt cable using the official Apple thunderbolt 2/3 adaptor.

All works fine - there’s slight blurriness when large windows are moved around on the secondary screen, but it’s perfectly tolerable.

One problem though - I have a multiuser setup - I share the machine with others in my family.
Each user has their own account on the primary machine. I’ve set up a dedicated account on the secondary machine called “screen”, which is where Luna Display Secondary runs - the idea being that when we switch between users on the primary, there should be no need to do anything on the secondary (i.e. we can treat it exactly like a second monitor).

Unfortunately, Luna doesn’t seem to handle fast user switching correctly.
If the user being switched to doesn’t have the Luna display app running, then the secondary display continues to show the first user’s screen (oddly the main screen not the secondary). Really the secondary display should go black in this scenario.

If the user being switched to does have the Luna display app running, it doesn’t seem to work at all - the user’s Luna display says “oops something went wrong” and prompts me to remove the dongle. Restarting either the Luna primary or secondary app doesn’t solve the problem. Switching back to the primary user shows that their Luna primary app is in the same state (prompting me to remove the dongle).

If I quit Luna Secondary and quit Luna primary for both users, then try again (launch primary for one user, launch secondary) it doesn’t work consistently; often I get garbage on the secondary screen and the primary screen intermittently locks up (this is fixed by quitting the Luna secondary app), but the Luna Display app doesn’t work after that (a machine reboot fixes).

I notice that there is a com.astro-hq.AstroLauncher process running for each user even when I quit that Luna Primary application. Could these processes be interfering with each other?

This seems like a show stopper for using Luna display in Mac to Mac mode on a shared computer, which is a shame as it works pretty well for solo use.