O Brother GeoBook, Let's Get Thou Back on the Internet?
oldvcr.blogspot.com
oldvcr.blogspot.com
The kernel (GEOS.GEO) in BrotherWorks is version 3.0 4-84, protocol 654.054. The archive.org blurb is correct that BrotherWorks is therefore GEOS 3.x.
The 2.0 Ensemble release kernel was 2.0 24-1, proto 654.001. NDO 3's kernel was 3.1 33-1, proto 654.060.
Oddly, the article looks at the GEOS.STR (a file of strings that the DOS start-up code uses for user messages and concludes that an unchanged strings file "proves" the GEOS version.