I want to translate an Eclipse RCP application based on Juno 3.8. For the Eclipse platform I downloaded the respective Babel language pack for German: BabelLanguagePack-eclipse-de_4.2.0.v20121120043402.zip.
Everything seems to work fine except for the buttons in the JFace dialogs: Cancel, Next etc. are not translated. The respective fragment (org.eclipse.jface.nl_de_4.2.0.v20121120043402.jar) which contains the translations is loaded correctly (I can see it in the plugin details) but the German values are not shown.
The bundle you have specified is for the version 4.2 (but you are using 3.8). This may be the problem.