I got this answer from Jesper, a colleague at NBTHK-EB.
Several schools use openwork, geometric and symmetrical designs. Normally one thinks of Kyo-Sukashi and Owari, but Shoami, Kaneyama and others use it as well. Kyo-Sukashi tsuba normally have a thin and fine design that is very symmetrical.
The school was very widespread and influenced other schools. A characteristic is that Seppa-dai and Ryo-hitsu ana tend to be quite slender. Owari tsuba is e.g. also symmetrical, but seem "heavier" in design. Higo tsuba, eg. The Nishigaki school also sometimes used geometric patterns.
The same goes for Shoami, Kaneyama and others, also Yagyo and Yamakichibei. We can therefore not only go by the design, but also have to look at the surface, e.g. Tekkotsu and Tochime, steel quality, etc. Eckhard Kremers mentions in his book Sukashi Tsuba that several tsuba attributed to Owari and (Ko-)Shoami may be Kyo-Sukashi. In other words, it is not simply…