I misunderstood. I thought you wanted the term for the period Queen Anne, the last of the Stuarts, was reigning. I don't think you'll find a latinate adjectival form for Anne or William. But here goes.

The term in English for Wilhelm II of Prussia is wilhelmine. The Latin for William is Gulielmus, so you could coin an adjectival form like the others, gulielmian, or maybe gulielmite. For Anne, how about Hannan, Hannian, or Hannine? They're all made up, but might be understandable.

Ceci n'est pas un seing.