You should post the tor@Arte1.service contents also.
If the service type therein is Type=notify, uncomment the PidFile and RunAsDaemon lines in torrc and try again.
There also should be the line TimeoutStartSec=300 in tor@Arte1.service.
That means systemd waits 5 minutes for a startup notification. If it doesn’t receive this notification, it restarts the instance. If tor runs as daemon, it doesn’t notify systemd. This causes this infinite restart loop.