Zemstvos have a lot of mysteries.
Wenden is in some catalogs and not in others.
Cuchin missed well over 100 issues in his catalog so non inclusion is not a determining factor.
From a History of Zemstvos
From: The Zemstvo postage stamps of Imperial Russia -Alex Artuchov 1987 (5 volume set)
WENDEN (Lifland) issued its first stamp in 1863, a year before the
Bill was signed which prepared the way for the normal Zemstvo posts. These
are the only stamps of this kind to receive recognition by our catalogue
compilers, yet the postal conditions of this region fall into the same category
as all the other districts of the Russian Empire. Whether the lawful right
to issue their own stamps can be traced back to a circular issued by the
Minister of the Interior, or to the political intrigues of the all powerful
Baltic Barons who undoubtedly enjoyed special privileges, which, in turn,
were shared by the provinces under their control, does not alter in the least
the character of the stamps. They are in every detail positively Zemstvo
issues. As they are the only stamps to appear in the whole of the Baltic
provinces, one must conclude that they owed both their introduction and long
life to the political power of the barons. The post was closed on 23. 4. 1903.
FATEZH, TIFLIS, ZEMINOGORSK, AMUR and a few others also fall in a somewhat grey zone as being Zemstvo's
Close-up of a Fatezh postal stationary issue