Hi Tony, Il use some guess work here, I have seen suede look wallpaper, it was a thin faux suede just like the upholstery faux suede only thinner, it's also used on lampshades, waste paper bins ect. so I would suggest its very unlikely to be real suede, maybe it was expensive so she thinks its real? or she just read 'suede'.
My first thoughts on this are, the water based paint may come off easy, but is the reward worth the risk?
I would think as soon as you wet it, the moisture will go straight to the paper backing, once thats soggy you could pull off lumps of wallpaper.
This job is not worth the trouble, swerve this one.
But then sometimes I get these things wrong and the job turns out piece of cake. A whiz over with a CFR tool might be all it needs.