I came here for the same reasons. I spent at least an hour+ trying all the different ways of installing the spigot to stop the leaks. I agree with other posters that it shouldn't be so hard to get a seal with the silicone gaskets. The drilled hole is a little rough but not terrible. If the drilled hole has a chip in the edge, I wonder if that affects the gasket seal enough.
As of about 20 minutes ago, my Bubbler is full of tap water and not leaking...finally. For what it's worth, this is what I did - The gasket arrangement was both gaskets tapering smaller towards each side of the the glass, which make sense. I lightly hand-tightened and then put water in the Bubbler. Then I started tightening and trying to center the gaskets in the hole. Sadly, it seems that it took more force than I thought it should've to stop the leak and I'm not exactly happy about it. I didn't crack the glass as far as I can tell, but the nut is as tight as my fingers could go with water in the Bubbler. I'd like to think that having water in while I did this made some kind of difference but it's probably just my imagination. Let's see what happens tomorrow morning.
I thought about the sealant idea for a little bit but decided that I would get other gaskets first. These are thinner than some other setups I've installed on large glass water containers and might be worth a try. Thank goodness my other Bubbler is not this type.
Hope you get yours dialed in so you can get to brewing!