I followed the webapp2 i18n tutorial entirely, doing thing exactly as said there. Still, I can't get my application to be translated when I change the language like Its shown in the last part of the tutorial.
Instead of changing the language, the application just keep showing "Hello, World!" in english with nothing out of the ordinary in the log console.
Thanks Jimmy for the time. When you answered I'd already found the solution and was testing it before writing here.
When you create the .pot file you get the following for each word you have marked for translation:
#: templates/index.html:10
msgid "msgid"
msgstr ""
When you create each of the translations you have a .po file in the specific language folder with the same line
#: templates/index.html:10
msgid "msgid"
msgstr ""
I made a mistake and instead of putting the translation inside the msgstr "" I put it in the place of "msgid". Obviously it wouldn't work, since the msgid is what bind the original message to the translation and the actual translation was empty.
Hope this helps somebody else.