I believe what you are talking about is a big misunderstanding. There is
no such thing as Wenden or Windish people!
Winden or Wenden was originally a german expression for Veneti and later
for all Slavic peoples. As the time passed, the expression Windish was
used to describe a Slovene living amidst a predominantly German
population (in Austria - Koroska or Karnten region) and Wenden for other
Slavic people who lived in the same situation (Polabski Slovani, Luziski
Srbi).
Already during but especially after the WW1 the expression Windish got a
negative connotation in Kartnten and Steiermark (Austria) and a special
theory (Windish theory) was developed, claiming that there exists a
special Windish population with its own language, different from German
or Slovene, which has not evolved to its written form yet. That people
were Slovenes speaking their language, which was a mixture of Slovene
(spoken and learned at home) and German (the official language). The
theory, aimed at denying these people their cultural identity and the
right to express it, became very agressive in the years after the year
1920. The category "Windish language" was first used in a 1939 census (a
nazi one).
A similar theory (Wenden theory)was developed in Hungary, where a lot of
people have emigrated from after the war and took the theory with them
to the States.
Barbara