Goldfish playing with bubbles from aerator at surface - risky?

I don't believe this is actually risky. Goldfish follow and eat things all the time that don't seem to make any sense. So long as you're able to keep them eating peas to p any air bubbles they might end up actually catching and consuming, there's no issue here. It's good to know your goldfish are healthy and active enough to chase bubbles and explore actively. Fish often go after bubbles on the surface just in case there might be something worth eating there, and then when they pop them and find nothing, they let it go. There's no real way to stop them from doing that anyway, so don't sweat it, just enjoy your goldfish. Cheers.