The v1.7.0 (2007-02-01) changelog for the UOP mentions the following: "Fixed a typo, "Uderfrykte Matron" is now known as "Udyrfrykte Matron" also changed all occurrences of Uderfrykte in the game to Udyrfrykte."
Maybe this should be reexamined, since the Udefrykte enemy in Skyrim also isn't called Udyrfrykte like in Bloodmoon, but has its own name. It seems like the wrong spelling of Udyrfrykte might be intentional. The USSEP also does not rename Udefrykte from Skyrim into Udyrfrykte.