Bromma is still a construction zone, so one should consider that it might not be possible to walk from tarmac to the departure gates. Occasionally security can be very jammed so if Norra is trying to make a very quick turnaround (say, start boarding people immediately after clearing incoming pax, Don't know is that possible though) and you have to exit/enter the terminal, there is a risk of missing the flight. But overall, ay sells connections with 20min connection time @
Bromma so should be quite safe not as safe as i.e. ARN would be.