If you start Rosegarden without Jack, you should get just midi channels, it shouldn't crash. However, as a test you can try to start jack with the following code:
jackd -d alsa
then start Rosegarden (note this will not give jack realtime priority, but first let's try to get the thing to run without crashing).
The last message
( CREATED OUTPUT PORT 3: out 1 - MIDI external device 0
Connecting my port 3 to 16:0 on initialisation )
seems to indicate that something goes wrong when it tries to connect midi ports. This person seems to have a similar problem, but no real answer
. It suggests trying another sequencer program, and see if that crashes too (muse is in the repo). I'm not quite sure what you'd gain from knowing that though
. If the problem is with alsa sequencer, the only thing I can think of would be to upgrade alsa-driver, alsa-lib and alsa-utils. I can give no guarantees it will work though, but it might be worth trying.
Since this problem doesn't occur for me and others I can only guess alsa doesn't like your soundcard an awful lot (or the other way around). Did rosegarden work for you on other Linux distributions?