Creating pages are broken: all parameters are ignored (title, width, and height). The page created always has title: Viewport, and size A4 in portrait mode. (maybe this is different in other locales)
# Rhinocommon
# all params are ignored here
pageview = scriptcontext.doc.Views.AddPageView("A0_{0}".format(page_number), 2000, 1000)
# this works
pageview.PageName = "mypage"
# but this is still ignored
pageview.PageWidth = 2000
pageview.PageHeight = 1000
# Rhinoscript
# all params are ignored here
rhinoscriptsyntax.AddLayout(title="mypage", size=[2000, 1000])