You mean you're lacking a Disciple of Dagon? The green cucumber hat guy? How... Never mind, I don't even want to know.
Editing is simple: find your save (usually in 'user/x-com files'), open it up in something like NPP and find the line that says
bases:
Then look for
name: [your super secret base name]
and then for
items:
and don't conduse it with craft inventory which has
items:
Then just add a line saying
STR_DISCIPLE_OF_DAGON: 1
under it. Voila, one fresh cultist for the Intelligence Lady to play with.
As to "Has Researched Church of Dagon", what you actually need is 'Church of Dagon Network'. Both this and 'Church of Dagon' show up under 'Reports' in Ufopedia. Church you should to have gotten already from a plain bearded cultist, though.