Poor plastered surface

Went to see a job recently (main living room) and was told by the HO that the walls had recently been plastered and painted but in certain light there are a number of faults with the plastering namely rippling which is all over the man large wall - looks terrible. Thinking of a very light skim of easyfil and sand back but some of this rippling is very shallow and I don't want the easyfil coming free.
The HO lightly sanded a very small area to highlight the problem
Any further suggestions