I tested with my copy of DE, and unfortunately it appears that old recorded games do not work on DE :|
MawBTS's recommendation for a "separate install of 1.0c/d/e so you can play old files," is probably the only way to view old recorded games.
I am uncertain if something like CaptureAge (https://captureage.com/) would be a convenient separate client that would work to view old recorded games.
Hopefully someone who has used it could shed some light on that as a possible solution?
“Strategy requires thought, tactics require observation”[This message has been edited by Saegan (edited 06-17-2020 @ 12:15 PM).]