I have a similar question five years later: Is the 4" matching back splash now out of style? And how long will it stay out of style? Doubt that it would be possible to get a full matching back splash 14 years after the home was built. I am considering removing the 4" back splash and going with a complementary tile or, perhaps, a colorful wallpaper. Thoughts as to how long the short back spash will stay out of style? (I'm old enough to remember bell bottoms - the first time they were in style.)

Have you thought about stainless steel backsplash tiles? https://www.houzz.com/products/4x11-honeycomb-matted-metal-peel-and-stick-backsplash-tile-set-of-3-brushed-st-prvw-vr~100903589. These tiles would look great with your stainless steel appliances.

I don't know what your client has in mind completely. It might be worth asking the client for some inspiration pictures for what she has in mind. I think some glass mosaics might be overpowering for that granite. But there are some glass mosaics that might work as long as they are very plain. Super white glass tile Maybe something like this with a tiny bit of pattern: Silver planks glass tile Or maybe this one which might work with the colour in the counter: glass mosaic - raw silk

OH BOY. I'm sorry I know you must be unraveled, but realistically it looks more like the counters dont go with your kitchen as they are brown tones and everything else looks black white and gray. Why did you leave the granite backsplash up? that would help minimize it a bit I think.. We need to see the whole room.