Is there a train to Paris CDG airport covered by the Pass?

Yes, there are from airport-ev 15 mins and direct and even continuing into central Paris in tunnels. This system is named RER and these trains/big metroś are NOT in the pass-system. It is run as a coöperative between the city-owned RATP and SNCF=the French big state railways. Depending on what terminal you land, it may be quite a challenge to reach the station where they go from. This station also has a few direct TGV=superfast trains to other regions of FR.

Note that when start from this Nord station you have to go to the special underground tracks for RER=far east side, furthest away from EU*. You can enter with a normal metro ticket, but cannot exit with that as airport has special higher zonal fares, so go to machine and buy ticket for this.

You probably will stay a few days in Paris to see this magnificent town and will hence probably ride the metro etc. Inform yourself on what tickets there are on ratp.fr or transilien.fr

You still can use the pass to make daytrips to favoured touristy destinations, near or further away. Now SOME of these lines going out of Paris are also in this RER system but still owned by SNCF-you should be able to use them on the pass, but will need to get a special free ticket from the counter to pass the gates-at start and end, and another one for coming back. If there is no counter or not staffed=bad luck. This is so complicated for those who have no railway education that I give up explaining it.

BTW-there are dozens, 100s of airports in about any country here in EUR that do not have any train. Some do not even have a regular bus, but those are tiny small ones. IF a city has a train to airport there are quite often special supplmts to pay-also with passes.