Northern lights, Tromso

the thing is that my return flight has a stopover in Tromso, so should I stay in town for a few days to take my chance too see the lights let's say from about 22.00 to 00.00 hrs if the weather is ok or is a waste of time

If see the aurora is the only thing you want to do there, don't bother. The chances are you'll have nothing but a few wasted days.