Anyone has the same issue that the left/right channels are swapped? Is there any way to reverse stereo, either of the game or via DOSBox?

There is a way to swap the sound of the stereo effects,

I use only for TV the DOSBox-0.74-MSS, there is a commend for the dosbox for swapping the effects,
the DosBoxMT has also the command for it, but I never used it before, so I can't tell you how it works there.

DosBox-0.74-MSS

command for the config

swapstereo=true