Correct usage of "visited upon"
Solution 1:
The phrase "visited upon" means "inflicted on", so it doesn't really make sense in the way that you are trying to use it. Your proof-reader's suggestion is reasonable. You could put "since the depredations of the Demons were last visited upon them."
Alas, for the pitiful mote sins that we cannot express in words; for them that suffering is visited upon us here which we carry secretly on our wretched body.
The Flowing Light of the Godhead, Mechthild (of Magdeburg), tr. Frank J. Tobin
Google Books Ngram Viewer: visited upon
Solution 2:
"Therefore thus saith the Lord God of Israel against the pastors that feed my people; Ye have scattered my flock, and driven them away, and have not visited them: behold, I will visit upon you the evil of your doings, saith the Lord." ~ Jeremiah 23, v. 2.