Painting, wallpapering, etc

[EnglishEdward]

You can paint on it and you don't see the seams?

Not from any distance, but the seams are likely to be visible at close inspection unless the paint is fairly thick.

An advantage of lining paper was that it was a cheaper alternative to stripping off the plaster
all the way to the underlying stone and then re-painting over new plaster.

A point to be aware of is that unlike replacement plaster, traditional lining paper is inflammable.

So too much lining paper and too much oil based paints could present a fire hazard.