You should think of Autocad's file format as a wrapper that contains the contents of the file.
Just because you save the file in an earlier version does not mean you have altered the contents of the file.
AEC content is, mostly, not backwards compatible, mostly.
Because there are changes to the AEC content that are unique to that version.
If its modified outside of it's original version then there is no guarantee that it work properly.
When content is saved back to an earlier version, the only reliable way is to -ExportToAutocad.
This will strip the AEC content down to lines and Arcs.
And you are correct. you can not use Object Enablers from other versions.
---------------------------
(defun botsbuildbots() (botsbuildbots))