can it be used on old concrete like roof tiles?

Hi, just to share my experience here...my living hall also facing the same problem because neighbour house is higher than mine too...I already tried more than 3 waterproof paints but none of them success...so, I can conclude that paint can't prevent the water from coming in through cement...you need to stop the water first before it reach and wet your cement wall...so, don't waste your time to try any waterproof paint and repaint your wall...

Like other member did mentioned, one of the solution to hide the mark is using tiles....but like what you said, very wired for a living hall....so, I also don't choose this solution...

Another solution is, hack all the plaster/cement out, apply waterproofing, and re-cement/plaster the wall....but I already moved in and don't feel like want to do hacking any more, so I do not choose this solution too...

What I do is I try to put some wall decoration to cover as much as water marks I can.....

Maybe applying Surfapore C kaw kaw could help with first removing the paint layer. That reduces water vapor coming through and condense at the paint layer. This is for Surfapore people to comment and give assurance.