Complex sentence: Possibly the work of foreign artists, they are of high artistic quality and appear to have been inspired by the Bohemian Master of Wittingau (c.1380) or the Wesphalian Conrad von Soest.
Split into simpler sentences: Possibly the work of foreign artists, they are of high artistic quality. The frescoes appear to have been inspired by the Bohemian Master of Wittingau (c.1380) or the Wesphalian Conrad von Soest.