In real life, the turn-and-slip indicator doesn't respond well to being inverted; such instruments usually 'tumble' when subjected to aerobatics. I'm not sure whether the Yak ever carried a TSI in real life (some WW2 Soviet fighters didn't even have a fuel gauge) but if it did, it wouldn't have been state-of-the-art, so I reckon AH Yak and LA jockeys should appreciate the one they have.
Hard luck, all those who don't use the superb RAF 'Basic Six' instrument panel.