My organization has been using CA SystemEdge agents on UNIX/Linux servers for years, monitoring those servers with discovered agents in Spectrum (and also CA Performance Center). However, it seems that the status of SystemEdge as a product is not clear. This might not be the right place to ask this, but perhaps someone knows if there's another SNMP agent that CA is promoting. The last version, 5.9, when GA about four years ago.
You should open a Support Ticket, then we can check with the Product Management Team the RoadMap for SystemEdge Agent.