May I suggest a cap of your pavers on the wall and the a slightly darker gray that relates to the privacy fence beyond? That way horizontal surfaces and vertical surfaces show similarities and blends/blurs the separations?

As the appearance of the garden has a modernist style with the straight lines and concrete furniture how about a Mondrian influence and add a bold strip of blue? It is a pond and with the right shade it could look really relaxed and contemporary. My daughter's suggestion is a chalky lilac!

If you have the possibility to paint this wall again in soft beige, do it. Then put a wide painting on the wall you have previously colored and fill the room with accessories of the same painting's color. You can change this painting every few years along with its accessories and have a new ambiance ever time!

I once saw a gorgeous grey house with a chartreuse door and lots of purple plants in the front of the house. Wouldn't work my (horrible) salmon pink house (one day it will be painted) but since you have the grey might be worth considering?