You can try using "ntevel" probe to monitor the event logs on the server and pick the errors related to DFS Replication by creating filters
Some of the error codes are listed below for reference
[MS-DFSRH]: Types of DFS Replication Errors
I believe even "adevl" does pretty much the same by monitoring the NT event logs associated with Active Directory. It monitors the event logs of Directory Service, Application, DNS Server, and File Replication Service for new messages and generates alarm messages accordingly .
v2.0 adevl IM GUI Reference - CA Unified Infrastructure Management Probes - CA Technologies Documentation
Not sure there is any specific probe for monitoring only DFSR