In the 2 years that we have owned our RV (which has the same papered walls as yours) this has never been an issue. The paper is impervious to water and does not get soggy, if that is what you are worried about.
It will hide soap residue well though and the only way to tell that it is there is to run the palm of your hand over the shower area and compare with the non-shower wallpaper in the bathroom -- feels slightly gummier.
I will be adding a stick on plastic enclosure walls similar to this residential bathtub wall kit
as a means of both upgrading the look and cleanability (?) of the shower.