Not too sure where bugs relating to packages like Gallery go...
Same place as "normal bugs" for Revolution?
MODx Revolution / MAMP / OS X
It depends on the author. Usually, there will be a link on the package download page (Google: MODx PackageName download) that will lead to to the bug reporting location.
In the case of Gallery, it’s here ("issues"):
https://github.com/splittingred/Gallery
