Hi, I've been trying to change the icon for the Adafruit.fzb file to have the Adafruit insignia instead of the default hexagon, and I've changed the icon xml tag. Where would the .png file go into what folder?
While I'm not real clear on what library you have (the github adafruit library repository I have from some time ago is fzbz files not an fbz file) in the github version there is a directory Bin icons which has the png files presumably for the icons. I expect you need to find a similar file (possibly be unzipping the .fbz file) and replace the icon there.
I just did this myself....