Regan on its own isn't very high in the popularity charts, I agree. But when you consider the spelling "
Reagan" which is almost in the top 100, the name itself is somewhat popular.
And the name isn't trendy everywhere in the U.S. but it is in the region I live in. Same thing with
Karolina. It's not even on the popularity charts for the U.S. but where I live,
Karolina's outnumber
Ashley's, easily.
And I agree with you on the whole Exorcisist affecting its popularity. Like you said, it came to the top 1000's likely because of the popularity of the movie, but has likely also been hindered by the movie's success.