T'ara greeting in Japanese in France?

In the pre-show interview at the Music Bank, Paris, T'ara members reportedly spoke  in Japanese, which stirred some debates among K pop fans. 

It is reported that after the photo session, Eunjung said, "Arigato," and Soyoun also followed her by saying "Arigato gozaimasu,:"

Some fans say that Eunjung actually said "A Bientot." a French expression for "See you later" but that Soyoun was clearly speaking Japanese.

Netizens agree that it was rather awkward that the members greeted in Japanese in France if they actually did.