I honestly cant think of a good solution, You know it is upside down, if I were invited into your home and used your bathroom, I would chuckle about it and know it is upside down.
But how many guest in your home are carpenters and would know it was upside down?
Maybe we can declare it a new style and was designed that way?
It does look ok in the photo, nice tight fit and looks clean.
I do not know what effect the rippled glass being on the wrong side will cause, assume is only cosmetic.
If you called me out to look at this and fix it. I would have to suggest a new door.
Once you turn it over and flip it around, put the hardware in correct location which would be on the other side of the door.
Only possible way I can think of saving that door, is to re skin it.
Will be a material made for this at the big box stores or others, will add 1/8" to each side 1/4" total, hinges and or door stops will need to be moved.
Really can be labour intensive to do this, Also will sharpen the son inlaw skills
Again, for me or another carpenter to come out I charge $65 per hour, it would be cheaper to buy a new door.
But if you have the time and skills, could skin it.