If you don't need the russion audio (the first one in this case), you can remove it easily by using
VirtualDub Mod.
Have you tried to change it through the playlist method I descrbed you?
Once you change the default language number in the right side of the playlist, you have to save it to file. Next time you want to play that movie, you'll launch the PLS (playlist) file you created
This way if you move BSplayer to another path you'll still be able to start it with the 2nd audio stream.
I'll look into your problem and if I can reprodice it I'll add it to the confirmed BUGs post :)