If you still have access to Citavi, and Citavi allows you to modify an output style, you could create an endnote “look a like” citation with the temporary (unformatted) delimiters like {Author, Year}.
What do Citavi “fields” look like if you display them? (Alt+F9 in windows MSWord)
Support maybe able to help more - to create a conversion Macro.
To contact Technical Support directly
1-800-336-4474 option 4 then 1 or
https://support.clarivate.com/Endnote/s/technicalsupport?language=en_US