Yes, it would be great if you contribute a Croation translation! You can zip the file(s) and email them to me at joe dot audette at gmail dotcom. I'll add them to the solution and commit to svn. As you continue to translate more keys or files just send me the new copies and I'll update them in svn.
Resource.resx is the main file but there are other .resx files to translate and there are also files that can be localized under /Data/MessageTemplates and /Data/HelpFiles
I will also list you on the developer credits page for contributing Croation translation files http://www.mojoportal.com/developers.aspx if you want a link or an image there just let me know.