looks good:) very smart idea going with the neutral grey sofa and adding pops of color with accessories that can easily be switched up.
you can go with multiple patterns and stick with the grey, yellow, and tan, and add some black if you want. (1st pic). you could go with a pale aqua blue color (or brighter aqua) (2nd pic) . or a darker navy blue goes good with yellow.

Navy blue or red.

jennyrf, I love the picts that you sent, thank you for the inspiration, I feel better about my decision.

It seems you do need something to link the areas of the rug couch and cornice together. The greys are outweighing the cornice wall. Also, your cornice is more traditional while your rug is more contemporary, so perhaps getting a rug that has a more muted contrast between shapes and colors would be better. Or a pattern that is more "organic" rather than geometric. Cheers!

If you don't want to spend the money on getting a new rug right now you could try finding a tray and/or centerpiece for your ottoman coffee table with similar patterns and colors as the rugs I posted above.