From a Czech specialist on the period, Petr Starosta, I have got some corrections on the ”Czechs dressed like hussars in Siberia 1919”.
The shown fellows are not in Siberia, but back home in Czechoslovakia 1918-1919, probaply taking part in the Czech-Hungarian War 1918/19.
They are most likely in Sokol uniforms.
The Czech Sokol ”Gymnastic” groups were weapon trained, along the lines of the Boy Scout Movement, and took up arms, just like in Poland 1918-19, as Czechoslovakia of course had not is own national army just after WW1.
Volunteer Sokol units made up almost 50% of all Czech troops in the beginning of the Czech-Hungarian War 1918/19 – and fought in their Sokol uniforms.
Petr also points to the medal worn by the officer, which seems to be the Czech Cross Medal, which was awarded for bravery in the mentioned war. See picture.
Somehow the French on
http://www.ecpad.fr/la-mission-de-la-spca-1918-1919http://www.ecpad.fr/wp-content/uploads/2010/06/spca.pdf have got something wrong, when describing and dating the photos. The other photos in the series are from Siberia.

Sokol uniforms

Czech Cross for bravery in the Czech-Hungarian War 1918-1919

Czech cavalry uniform in RCW

Czech cavalry uniform in RCW

Czech standard in RCW

Czech standard in RCW