Hi Sven,
Unknown matches Don’t care.
Conflicts are still possible, but if e.g. On is configured for one position and no other position uses the same On event, then it can work.
Another thing that might be an issue is that if a node sends two ON events, traintastic will ignore the second, because the internal cached value is already ON/true. Can you check the log if that happens? (Or create a diagnostic report 
)
Greetings,
Reinder