Not necessary.
Exactly. And again, no need to script if you have a macro or keyboard shortcut app such as KeyboardMaestro, Typinator, etc. Just turn the two DEVONthink shortcuts into one macro.
Anyway, if you really want a script then use this. Use at your own risk. Tested to work here, but I don’t have your data and no support will be provided:
use AppleScript version "2.4" -- Yosemite (10.10) or later
use scripting additions
tell application id "DNtp"
set theDB to every record of the current database
set theDestination to "~/Downloads/DBE"
repeat with thisItem in theDB
set theResult to export record thisItem to theDestination
end repeat
end tell
If the destination folder does not exist, the folder will create it. If the destination folder does exist, the script will create a duplicate folder for everything exported. A more sophisticated script could catch that behavior.