The Czech sub-community has produced a Czech street list. It is based on manually curated address data of the whole country, and includes around 4 thousand items.
You can get it from pak128 svn:
http://simutrans.svn.sourceforge.net/viewvc/simutrans/pak128/pak128.prototype/text/streetlist_cz.txt?view=log
Please note that if you want to view the file's contents, it is encoded in 8859-2, as required by Simutrans.