There is a list of current categories and a set of pages where agreed translation of those categories can be found, linked from Translation_Help_Needed
As a general principle:
New categories should only be considered if no existing one can be applied. If a new category is essential it must be added to all the translation tables listed on Translation_Help_Needed. Application-name categories may be omitted from those tables, as they will only be translated for non-latin alphabet languages. The translator is expected to know the official glyphs for the name translation.