Well they could of course. Have you inquired with the devs over on the Emby forums?
There is a standard for XMLTV data that all of these different PVR/DVR devs should follow and a lot do:
<episode-num system="dd_progid">EP02843356.0007</episode-num>
<episode-num system="xmltv_ns">0.6.0/1</episode-num>
Emby does, NPVR does, Sage does/did I haven't played around with XMLTV and CDVR (I like the X-M3U feature) but I would be willing to bet that CDVR does too.
All that being said I don't know if it is even possible using the current XMLTV export feature of CDVR to provide the standard mentioned above. It would be great if it could.
I am hoping that Emby (in their "Next Gen LiveTV update) incorporates something like the X-M3U feature that CDVR uses and all this will be a moot point, add the station ID# to your M3U file for each channel and you are done it pulls the correct EPG data for each channel.