First, my congrats.

I love Matcha, it's the natural successor for Arc and you have made such a great job during all this time. For XFCE, Mate desktop and even Window Managers as Openbox or Fluxbox is my go-to theme. I've played a lot making my own themes via oomox and simple stuff like that and I would like to suggest an idea I had. Matcha is a simple minimalist theme that doesn't get on the way, I like it but sometimes the color accents are too much for me. I would love a simple take on black accent Qogir White icons (I will create a separate issue for Qogir). To achieve something like those following images but on a good maintained theme I can trust: