bohm:
Using the same building is one thing. They reduce the numbers of congs. This is a sign for a decrease.
The difference between language/sing-language-congs and normal cong: less publisher, they very easy going (eat after the cong...) and much more. So they reduce congs they started years before with 80-120 publishers and make new (language)congs with maybe 30-50 persons, runned by 10-20 publisher they also attend the german congs from time to time.