Comments - CorruptedArchangel

More than likely if they were ever to be added it would be an earlier start date, such as when the Ayleid and Chimer were still around.

I'm not a hundred percent about this but you could try surveying counties in Skyrim, if there is a county called "Korvanjund" or a derivative of that name it will be there. Same as you can get the "Amulet of Kings" from "Sancre Tor"

Well first of the Warlord CB only functions against those in your cultural group (possibly religious too), granting you all the land occupied in the war (yes all the land). The many CBs you listed are not bugs those are separate reasons for war with different benefits. Warlord would grant you personally the Duchy you declared for and vassalize any non-crown-owned land occupied, a de-jure claim would be claiming a (singular) county that has be rightfully declared as apart of your realm or that of a vassal's (e.i. a county belongs to a duchy, kingdom, or empire you/your vassal own), and finally unite Morrowind is pretty self explanatory it is you trying to reunite a known cultural union through conquest by duchies.

Though to answer your first question yes you can declare outside your own cultural borders, you can use the fabricate claim function that the chancellor possesses. Look at a de jure map (duchy, kingdom, or empire (never create 2 empires)) fabricate on 66% of a region and conquer it. Then you can create the de jure title and vassalize or lay claim to the rest of that de jure land.