1972 universal remodeled

[Tina]

My dad, age 91, is looking to purchase a mh that's been updated as follows: exterior repaint, new roof, ac and heating, kitchen, all new double pane windows, R19 insulation installed under original panelling which was then replaced and drywalled over, then wall paper. I read something about it being a bad idea to insulate and dry wall over MH's with "exterior vapor retardent". This is all very disconcerting as I'm concerned about possibiity of mold in the walls and other stuff I have no clue about. Could someone give me some insights and advice on how to check up on this or if I need to. Thanks for any help.