Ok, localization complete!
I removed the old reading menu and bookmarks menu and placed instead two new kindle-style menus.
This helped me reducing the amount of button images to be localized (now 14).
I changed the html range input with a new jquery ui to choose the scroll amount.
I also localized the launcher menu and added a new script to change the menu language according to the system language.
All scripts (rename/delete/move screenshots/decompress archives/check updates/sounds) use now localized on-screen instructions.
Finally, both Komic and its launcher menu have en_GB/it_IT languages and they use english as fallback language (i.e if they can't find a correct translation, they will use english).
New languages can be added, if someone wants to help, please let me know (it's an easy job, although there is quite a huge amount of strings to be translated
And now some screenshot (in italian obviously