I took the colored bits to be transparent enamel. That combined with fine line schwarzlot in this style was, as far as I know, most common at Haida, Steinschönau, Wiener Werkstätte, and (I think, though I haven't been able to find examples in a quick search) Josephinenhütte. Of course, Wiener Werkstätte was in Vienna, but it seems to share a lot of stylistic similarities with northern Bohemian work. I've seen those little spirals a lot in work from Steinschönau.
Ivo, who in Sweden made glass in the same style, with simple black lines and enamel? What makers in southern Bohemia used it? To me it seems pretty distinctive.