I don't know if I should be reporting this here, but it's translation related. In the build menu information about the translation file is appearing and I believe it shouldn't. The attached screen-shoot explains it better than words.
I tested with pt_PT, pt_BR, de_DE, en_GB and en_US, by executing geany from the console with *LANG=pt_PT.utf-8 geany* Only in the latter (en_US) there isn't any problem.
Kind Regards, André
Ps: Thanks for the "Add custom filetypes features" I have some friends that will be changing to Geany because of that.