Hi,
you're not giving much information regarding your setup, so I'll guess.
The recordings should be in /var/bigbluebutton/published/presentation in your SL server. Each recording has its own folder. You can pack (tar) each of these folders and transfer them to the new SL server with scp or rsync.
SL has a docker container which monitors the /var/bigbluebutton/spool folder every 60 seconds. If you put the tar files in said folder on the new SL server you should get you recordings back.
Regards,
J.