The Vienna at least is bookable on FR and again it only makes it a total of daily. Eurowings have been superb in letting the route have time to bed in but passenger figures have been low and it has suffered many cancellations or days where it normally operates but was non-ops.
Do Eurowings interline with Austrian at Vienna? If so, perhaps their reason for being on the route is more to do with that, than shipping weekend breakers to eat exorbitantly priced Apfel Strudel and coffee in the Austrian capital.