Regarding the errors you’re seeing around qpid/qdrouterd: you don’t need those if you’re not using katello-agent. Although, you should definitely look into using Remote Execution instead.
If you need katello-agent, then re-run the installer with --foreman-proxy-content-enable-katello-agent=true which will set up those up on your Katello server. If you don’t intend to use katello-agent with your clients, then you can safely remove the katello-agent package from those systems.
Ok, for last checkin time: as far as I know that gets updated in two situations:
when the rhsmcert daemon on your clients communicate with the Katello server. that’s every 4 hours by default
when you run subscription-manager refresh from your client
Which of those (or other scenario) were you expecting to see the checkin time be updated?