Films from other countries - including American, French, German, Czech and Russian silents, were shown in Poland alongside Polish-made fair. Those imported films included Brooks' American, German, and sole French film. So far, I have been able to document the premieres of both Lulu (the Polish title for Pandora's Box), Prix de Beaute and other films in Warsaw, the capitol of Poland.
I found out, for example, that the Casino theater in Warsaw, the theater where Lulu was shown, was a major cinema in the Polish capitol.
The great thing about Law of the Looking Glass: Cinema in Poland, 1896-1939 is that it offers clues about where else to look for material about Louise Brooks and the reception of her films. Skaff's book discusses the surprising number of film publications (both industry journals and fan magazines) which were issued not just in Warsaw, but also in Krakow and elsewhere. Of course, accessing those publications is the tricky part. Few American libraries have them.
Happily, I was able to search through a couple of Polish publications over the web. Here is a piece about director G.W. Pabst which mentions Lulu. It is from Kino: tygodnik ilustrowany from 1932.