Since you've already compiled pktriggermode and tested the change in pslr_model.c, perhaps it's easiest to keep working with pktriggermode directly to see if we can find the right solution. I think it'll be easier to mess around with the cli (pktriggermode_cli.c). My first thought is to try calling pslr_shutter again before calling pslr_bulb at the end of bulb_old. So to be more specific, try adding "pslr_shutter(camhandle);" between lines 339 and 340.
My next thought would be to force the K30 to use bulb_new instead of bulb_old.
If you can do either of those, let me know how it goes, or let me know if you need more direction.