I would think someone on the manufacturer's staff should be leading the way towards a solution, if it indeed is a mfg. fault. Just off-hand, the shower door situation might be easily fixed by a change in procedure, holding the glass panels apart during transit. It could also be that replacing the glass with acrylic sheet solves the problem. Might be many ways to a different resolution of the problem.
Unless Keystone has every owner complaining about non-operating windows (I don't know whether that is or not the case), then it would seem that MB's trailer has a unique issue. It may be that the frame is not right and by typical installation process, it is racking the window jambs so the window doesn't operate correctly.
I wonder if the OP might know the reason for the windows not operating?