p96, the entry "Chinese pieces" says "introduced to a wider European publicity by P.Seyfert-Bitterfeld in the February 1936 issue of Die Schwalbe".
Also of interest the French book Le Guide des échecs, Traité complet" by Nicolas Giffard and Alain Biénabe (sadly passed away in 2021, see https://www.echecs64.com/2021/02/28/deces-du-problemiste-alain-bienabe/ ) has a very strong part dedicated to Fairy Chess (I don't know something as complete in English) written by Biénabé. Page 1200 it presents the family of Chinese pieces and says (my translation):
These pieces were "discovered" (from Chinese chess) by P.Seyfert in 1936, but it is T.R. Dawson who gave their first noble letters to this family!
I found an interesting source. Encyclopedia of Chess Problems.-Milan Velimirovic Kari Valtonen.2012-Comprimido
in:
https://fr.scribd.com/document/536275573/Encyclopedia-of-Chess-Problems-Milan-Velimirovic-Kari-Valtonen-2012-comprimido
p96, the entry "Chinese pieces" says "introduced to a wider European publicity by P.Seyfert-Bitterfeld in the February 1936 issue of Die Schwalbe".
Also of interest the French book Le Guide des échecs, Traité complet" by Nicolas Giffard and Alain Biénabe (sadly passed away in 2021, see https://www.echecs64.com/2021/02/28/deces-du-problemiste-alain-bienabe/ ) has a very strong part dedicated to Fairy Chess (I don't know something as complete in English) written by Biénabé. Page 1200 it presents the family of Chinese pieces and says (my translation):
These pieces were "discovered" (from Chinese chess) by P.Seyfert in 1936, but it is T.R. Dawson who gave their first noble letters to this family!
According to British Chess News, https://britishchessnews.com/2019/12/16/remembering-thomas-rayner-dawson-28-xi-1889-16-xii-1951/ Leo (and Vao) had been invented in 1912.