Hi @Anthony Raymondo
I can’t say I’ve come across this information - or question - before.
“Airtight” is not something that can be specified without also expressing some sort of pressure differential, but as we’re just talking about air rising due to heat, this would be minimal.
Looking at the pictures of the Sonance In-Ceiling Speakers I think it’s safe to assume that if the speakers are fitted properly, any drafts would be minimal. You might be able to seal the fitting - a large O-ring or a silicon application may help, but I would test any silicon on an unseen surface first.
If it’s more important to you to ensure no escape of heat than to have In-Ceiling speakers, perhaps Sonance In-Wall Speakers or Sonos stand-alone speakers on wall mounts would be a better fit for you?
I hope this helps as it is all I have - if you wish for more information or assurances, I recommend you contact Sonance directly - Unless anyone in the forum has looked into this?