'Plaster other side only'.

Lol, a common mistake, when they manufacture the board, the liquid
plaster filling is poured onto the lighter paper and it binds with the
paper fibres, the darker paper is then layed on top with the lighter
sides folded around and glued. The bonding strength of the darker
paper is below specification and is NOT for sticking ANYTHING onto it,
especially something wet that soaks through the paper to the plaster
filling weakening the tiny area around the nail or screw used to fix
the board to the surface.

Thats why they take the time and money to print the words "Plaster
other side only" onto plasterboard.

On a ceiling with heavy light fittings fixed to the board with
condensation or a water leak could bring the ceiling down, but in your
wall/tile situation it will be fine, just dont fix anything heavy like
shelving to the finished wall.