This was supposed to be Tanya's party, and she was definitely frustrated—even visibly agitated by the fact that she was being given the cold shoulder upon the news that Kathleen was coming.
She owed Yoshitaka due respect because the man was basically her boss, if not the boss of her boss.
On the other hand, Kathleen definitely wasn't her boss or a shareholder of Universal Music, let alone showbiz.
So, why should she let Kathleen steal her thunder?
As such, she kept a lid on her frustrations