Again, there is no such thing as importing recordings from one server to the other. You either import the BigBluebuttonBN activity (which includes the meetingID generated when the meeting/recording was created) or copy paste the link to the recording manually (but as a link not as a recording)
You may want to look for procedures to backup/restore databases.
The versions are important because the backup/restore feature was not working properly before. I don't recall in what version the feature was fixed. You may be able find the reference it in the RELEASENOTES file. So, you have to generate the back up with the latest version and also restore it with the latest one. Otherwise it may not work.