Hi, I use an EA to indicate the version of JC installed on a Mac. Or you Jamf's Patch Management to see the version is installed on a Mac.
if [ -a /Library/Security/SecurityAgentPlugins/JamfConnectLogin.bundle/Contents/Info.plist ]
RESULT=$( /usr/bin/defaults read /Library/Security/SecurityAgentPlugins/JamfConnectLogin.bundle/Contents/Info.plist CFBundleShortVersionString )
If you're also a Jamf Pro customer, look at the list under Settings > Computer Management > Extension Attributes > New From Template > Jamf Applications. You can enable several EAs for Jamf Connect reporting there.
Otherwise, you can use the version from the Jamf Connect.app found in the Mac's Applications folder. This is effectively what one of the EAs is doing. The other EA will provide you the Jamf Connect login window version.