The missions ending in .kth are missions for the Kriegstanz tool developed by Floater
http://www.brookview.karoo.net/Kriegstanz/
They will not work directly in PA or SH2, but instead you have to drop them in the main folder of Kriegstanz and then launch the tool. You will then be able to select the mission in the KT menu and benefit from the randomization KT provides
Missions for SH2/PA are always with the extension .SDF (Which BTW means "Scenario Definition File" and can be opened and edited with notepad, wordpad, word...) and would go into Pacific Aces/Shell/Scenarios
Good hunting