I would like to participate in this open source project, but I think I am not familiar with some GUI development since I am currently mainly engaged in the development of the pure image processing algorithm.
The GIMP Beautify plugin is using GTK just like the GIMP core code. You can study the GTK first. This need spend some days.
And do you interested in maintains the wiki for this project? We need someone to translate the GIMP Beautify tutorials into the wiki. (we already have a lot of GIMP Beautify tutorials at baidu tieba but in chinese language). This need familiar with GIMP and GIMP Beautify plugin.