Someone other than the devs
might do it for you, but you
can do it yourself if you don't like waiting in indefinite uncertainty.
Toolbar icons are in the Reaper Resources folder > data > toolbar icons. Edit then however you like.
I think the best medium point is icons with a textual hover icon, which is what I'm about to do with mine.
Note that this is purely subjective. To my eyes, anything with text is confusing, but I'm well familiar with all my icons and their functions.