I flew B7 170 from TPE to ICN last Thursday. Here's the scoop on the entire deal for Star Alliance Gold members.
I used the Star Alliance Gold desks for check-in. After the passport check, the agent asked for my membership credentials, which I produced my United Premier Platinum card. She processes me, my bag, etc. and informs me, (translated) "I'm sorry but since you are flying UNI Air, you will be unable to access the lounge and also I cannot expedite your checked luggage either. You will also be unable to earn mileage on United for this flight."
This flight boarded from a bus gate and there was no real semblance of Zone control either, but the flight did board in an orderly fashion.
The flight was uneventful and because the plane was a quarter full, better than normal service from the FAs aboard the flight.
If you need all the benefits that Star Alliance Gold can get you while flying, I suggest avoiding UNI Air.