A wall feature for the fountain?

Everything is too short. Put something higher up

You could try a vertical garden, using Wooly Pockets or use a tall tree stump to mount bromeliads onto.

you should look at more landscape photos as the arrangement of plants and accessories are not complementary. Houzz has millions to get ideas from

Nature likes things in threes and fives. The two tables together aren't working that well. I agree that warming up the wall would help, or a fast growing creeper on it like bignonia or bougainvillea, together with creeping fig. The plantings could improve with density and height. Use stands and pots to achieve this with annuals while you wait for perennial installations to grow in. I think you are on the right track, but you need more lushness (big tall plants in clumps of three or five, and some rounded shrubby ones, then fill in with annuals and spreading vines like you did at the fountain area. Think of each wall as its own landscape painting, look for movement in the "horizon" line, colors in the foreground, midground and background.