As much as I hate making changes this late in the game, I've decided that I really need to modify how languages are added to FeedDemon. These changes are necessary in order to simplify installing new languages, both for end users and for translators (not to mention myself!).
Starting with RC3 (coming next week), all displayed strings will be contained in one XML file per language rather than three, and each language file will be stored directly in the Data\Lang folder rather than in a subfolder of it. FeedDemon language files will be named after their language, with the extension .FDLANG (ex: English.fdlang, Spanish.fdlang, etc.).
If you've translated FeedDemon into another language, you can simply copy the text from the three older files (const.xml, dialogs.xml and forms.xml) and paste them into your new FDLANG file.
Note that several strings have changed in RC3, so additional translating will be necessary after creating your FDLANG. To help with this, I've uploaded my English language file for RC3. Each new/modified/deleted string has been marked in this file with an "RC3" comment, so simply search for "RC3" to locate changes.
If anyone would like to create an FDLANG prior to the release of RC3, let me know by posting a comment here once the translation is completed, and in your post please state whether I have your permission to include your FDLANG with the RC3 install.
BTW, be sure to save your FDLANG as UTF-8 if you use accented characters - otherwise, the accents may not appear in FeedDemon's UI!