Not quite sure what you meant by "making its way to sealing surface". Shouldn't the sealer be contacting with the sealing surface for better seal? I thought that's the purpose of the sealer.
the machined boss/groove area. I peaked at the speedbleeder sealant... it looks like their install instructions specifically call out what @definitely not a cat is saying.
To answer my own question, I just unscrewed the bleeder and measured, it should be a M8*1.0 bleeder screw.