That’s actually not easy to find, but easy to fix, of course from Internet Explorer, it has nothing to do with Sharepoint, at least that is my current thinking I am glad to hear any comments on the matter.
Problem: We have custom actions in the ribbon, the name and description from these actions are coming from resource files. In Internet Explorer once you select the language, then in the ribbon you will see the correct language for the custom action labels. However if you then select a different language, you will see the labels for the language that it was set before that one. It doesn’t change.
How did I get to the solution: I checked all resource files and they were fine, we reset IIS, we executes stsadm –o copyappbincontent, we checked all feature receivers to see if there was some code conflicting with it
Then I decided to try in Google Chrome and in Mozilla Firefox. Well, the translations works fine there, so I thought it was a cache problem from the Internet Browser itself.
And Indeed its
Solution: Internet explorer Developer Tools, F12.