Into what language do you need to translate these? There is a community-based translation project that may already have your language (partially) translated. It also links to the documentation for the proper translation approach and a mailing list for translators.
Translate to czech language, but today i comunicate with some people and find the solution for that. I am in crowdin translator team. Alfresco from version 5.0 change somthing and now i must manually put translation files into tomcat\webapps\share\WEB-INF\classes\alfresco\messages, because jar file from crowdin translate doesnt work for some string like in attachment.