Did you try in a rich client? Does it work?
Having two windows open at the same time, picking references out one by one, is certainly an ok experience - it's just not a great one. Ideally, there should be some kind of multi-selection, preferably within the same browser tab. It's what users have come to expect. But I suppose that's the state of WebUI at the moment.
I appreciate you taking the time to make a gif demo! The way you demonstrate is better than the setup we've used.