Implemented jcome's flat icons but can't seem to change zoom in/out/fit icons

I implemented jcome’s flat icons from the git repo (github.com/jcome/synfig_ui). I changed the palette to make it work better with a dark theme and I think they turned out pretty well:

However there are some icons i can’t seem to find to replace. Specifically Zoom Out, Zoom to 100%, Zoom to Fit, and Zoom In. Is there any way to change those icons?

Those icons are from gtk theme, you can have a look to from those part 1 and 2 of the code.

Have a nice coding session