Dorothy, I know a brain surgeon and an airline pilot would you like me to fly you anywhere or ...?
Medlands is not a primary source it is a secondary source which quotes a lot of primary sources, the fact that people on Wikipedia quote it as a source makes them no better than us here on Geni. Unlike Geni and Wikipedia Medlands is not crowd sourced it is maintained by Charles Crawley so I have no idea what you mean by "joining it", as for mistakes well I will be very impressed if you find a historical error with Cawley's work. Broken links and typos happen but the data is very high quality.
As you say Medlands is continually being updated, I have taken to the habit of adding the version number and date (found at the top of each Medlands page) when i copy text to Geni and i encourage everyone else to do the same.