that's likely Gorilla Glue 5 minute epoxy, very available , HD too, google it
I'd do 2 T-nuts at a time , so small batches and no worries about it cooking off too fast - and it does
i put only a smidge into the hole wrt to the t-nut barrel -
AFTER i had a bout 1/8" insertion , trying to keep the threads virgin
of course everything has been dry-fit(ted) to death
including driver fit to that part of the baffle
IF there is some t-nut metal overhang beyond the edge( which you've slightly eased)that you think might be hazardous to driver surround travel at "full" throttle,
file / grind it off
take you time and enjoy problem solving process / procedure.
you want it right, once, the first time.
8-24's should be plenty of good holding power, maybe washer head for more surface area squish
I usually use a 2" wide fiber re-enforced 1/8th" plumbing tape as gasket material. cut to a more usable BUT FULL width
which answers the question: did I compromise on getting this sucka' sealed