How do I find out
the final agent that received the call when someone called a CTI Route
Point, using CDR data.

I apologize I really don't know a whole lot about Callmanager / CCX. I'm basically a C# developer. So far I have managed to get CDR data using CDR flat files and backend Informix db using data dictionary documentation.
Do you mean Historical Reporting Client? Is that the only way? How does HRC know the agent who answered the call?

For anyone who comes across this post: CCX has its own informix backend database, separate from callamager CDR system, which keeps track of its own "agent CDR" if you will.
HRC provides a GUI based interface plus a scheduler which connected to CCX database, and which can, among other formats, output CSV. This CSV can be parsed or whatever if you want to use your own way of searching agent call details.
But in a nutshell - from what I can tell, you wont get agent CCX extension in callmanager CDR.
EDIT: agent extension is available in callmanager CDR. the originalCalledPartyNumber or finalCalledPartyNumber will not reflect the CTI route point number. Do get agent cdr, search by globalCallId_CallId of the original call that came to CTI route point.