Looked up both outfits and I agree with you about both. I wonder if the Celine look was put together by someone at Celine (doesn't look like Hedi's work to me) or by Gaga herself.
Oh sorry for not answering earlier, Celine was in Dior.
LVMH was an official sponsor of the event so they paid for the right to make exclusive contributions through various houses: Dior for some performers (Céline, Gaga, Aya Nakamura, Zaho etc), Vuitton for the French athletes, Brigitte Macron, and the stewards bringing the medals too. Not one single good look, barely passable, but of course Dior held an exhibition of the dresses.
Vuitton for the trunks carrying the Olympic torches.
LVMH did an official campaign with athletes on top of the LV Foundation.
But I did not spot Celine except on Gaga; Celine does not have the same immediate recognition.
The alcohol brands were obviously banned and the other brands not represented.
For the rest of the Olympics (ceremonies), the stylist Daphne Burki had very questionable taste, the most offensive being some Charles de Vilmorin suits.