Anyone use a U.S. VACCINE CARD to board a TGV TRAIN at CDG airport after Aug 15, 2021?

I'll link you to my post from the other day. It's about a note from SNCF about that exact issue. The answer seems to be that the CDC card will work as well:

https://community.ricksteves.com/travel-forum/covid19/message-i-just-got-from-sncf-re-riding-trains-with-qr-code

And from what I've read in the French press, the SNCF isn't checking every passenger as that would slow boarding too much -- so there will be random spot checks instead. I'll be heading for CDG's TGV station early in Sept., so I guess I'll find out for sure (I don't trust the QR generation process coming through with a timely delivery very much).

They definitely are not checking every train, they don’t have the staffing to do that. It will be hit-or-miss.

When I was at Gare de Lyon the other day to meet my husband (he was returning from Turin), there were volunteers checking anyone who wanted to enter the spots closer to the actual boarding areas. They were asking them for their pass sanitizer, and then if the person had one, they gave them a blue bracelet so they didn't have to be checked again. So it's possible that you might get stopped in the station, even if there's nobody checking your actual train. (I went through without getting checked. I had my QR code but nobody asked for it.)

UPDATE:

Unfortunately, this travel segment was not stress tested as nothing was requested as far as a health pass is concerned when boarding the train or while on the train. BUT, we discovered a pharmacy next to the train station in CDG T2 where an antigen test can be obtained for 35 euros each. Previous online research indicated that the only antigen test available there was for departing airline passengers only and with ticket in hand. Apparently, there are two locations there; one of which we could obviously use as non-airline departing passengers. Again, this was not known prior to arrival at the pharmacy and not for a lack of trying to find out on the internet. We stood in a short line and received the antigen test and resulting QR code in short order.

Also, the vaccine certificate of equivalence application was sent in on August 18th with an August 21st arrival date in the subject line. Still have not received a reply.

Traveled TGV from Avignon to Gare Lyon Paris on August 11th and my boyfriend traveled trains from CDG to Callais on August 18th. No one asked for our vaccination cards.

Same here. We traveled from Montparnese to Bordeaux and back on the TGV train and they never asked for any health pass either way. We did purchase our tickets in advance online so I can't say whether or not they would have asked at the office.

I have never read anywhere that the pharmacies in France are only doing antigen for departing ppl...

The reference to the COVID test for departing passengers only was for the location at the CDG airport. There is a testing location there that is only for departing passengers.