Okay guys,
So, I've read through two of the books that were in the bag so far. I've decided to scan the pages which had notes on them, so that you could have a look at them.
I'll elaborate once I've gone through all of the books.
Download link to the scans
The first one is "Ecclesiastical Oddities," and seems to be a collection of essays about various aspects of... religious architecture. yeah. A lot of them seem either religiously or mythologically orientated.
Marcusson's notes were specifically found in a chapter on sacrifices used to support constructions, both houses and churches. I still don't know what to make of this.
EDIT: I expected 'Mysticism - True and False' to be a little easier to understand what Marcusson tried to say, but I am still at a loss.
That said, he was working off what seems to be the writings of a madman. Sure, a madman with the Pope's apostolic blessing, but this has to have been for people of extremely special interests, even in 1918.