A recurring problem is that translators add the language code to the English category name, instead of using a completely localised name. We have some agreed names for most categories in most languages, linked from Translation_Help_Needed. If the category you need doesn't have a localised entry there, please add one.
When you add the new category name in place of the English one, you may get a red-link. Visiting the English equivalent page, you will see a one- or two-sentence description of what the category contains. Please add a similar description to your language category page. Thanks.
At some point we will need to clean up all the pages that have been wrongly categorised, to make them more useful to readers.