The first doesn't worry me at all. If there is KDE 3 content on a page, it should be in that category, to draw my attention to the fact that it will eventually need editing out. That's the whole purpose of the category - to enable us to find material that needs deleting or editing, when the time is appropriate.
Actually, I'm not sure that the second one matters either, as the KDE3 category is a hidden category, intended for administrative use only. It probably doesn't help to have localised versions of that. When the English page gets edited the translators will automatically get the changes in the normal way.
Perhaps we should start removing [[Category:KDE3]] markup as we come across them. (We would first need to make sure, that those pages have the {{KDE3}} somewhere). Or do those explicit category markups still serve a purpose?