All module text params (messages, notifications, etc.) should be printed with the joomla API JText::_(
language string) function.
As it is now, on a multi-language site, a module like JFBCInvite forces the administrator do go install as many modules copies as many different languages on the site. Why? Invite Button Text, Content URL Label, Invite Content, and many other fields must be in different languages.
You also should considering
NOT forcing some moduleIntro Text" and "No FB User Intro Text" on your modules.
Example from mod_jfbcfriends (but it is a standard on several, if not all, modules):
- Clean up the "No FB User Intro Text" and save: you'll get a default "Please log in through Facebook to show your friends that use this site" message
Well... as a site owner, I must have the ability do leave that message blank
Anyway, I am using my own module templates to solve this limitation, but this shouln't be necessary (and I risk to have to do it all again in future module releases...).
Please consider updating your module templates to be multilanguage...
Thanks