The DNs a call transverses are strictly dependent on the PBX you use [and the ISCC method used].
CDN is a generic term to indicate what in Genesys is configured as a RP - don’t get yourself confused by the PBX vendor vs Genesys terminology - two words can actually mean the same thing.
If you work with a regular default/route ISCC method, your description above is fairly correct; the main incorrect elements are:
agent reservation: can come along with ISCC, but it’s not part of an ISCC transaction
when TServer 2 has received the request from TServer 1 for routing to agent 2, it reserves an ERP and communicates back to TServer 1 the way it can hit that ERP [typically an Access Code]
TServer 1 then dials via switch 1 that Access Code - when switch 2 gets the call, it signals TServer 2
I do suggest you study any TServer guide where ISCC is widely explained.