Ceiling sealing now pretty good but

The electrical box for the ceiling fan is now sealed adequately as shown at left.  I didn't see any holes except a tiny spot on the big gap at 8:00 in the picture at right.  I'm not sure if that spot is a tiny hole or a spot.  When I was finishing up the sealing last Sunday (I worked on it Saturday and Sunday) I rubbed around the perimeter of the sheetrock with my finger to remove excess caulk, and that is when that tiny spot appeared.

I checked it out and took this picture on Wednesday, and observed that there is a slight depression in the largest hole area (that same one at 8:00) that could be filled with a bit more caulk, and I will do so, and that should fill or cover up the spot that may be a hole.  I could do some more caulking also, to make the junction more beveled as I have done for the outlets, but that's hard work especially on a ladder, so I'm not sure if I will bother.  (Some of the hardest work is mainly in the cleaning up after the caulking, making sure not one dot of excess caulk is on the sheetrock or inside the electrical box.)  And then paint over everything.  I'm not sure if I will do all these things, actually I think the perimeter sealing is now (finally) done sufficiently well just to move on.  In case you forgot, this is what it looked like before the caulking (that's like night, and the above is day).

I have also been planning to add a ceiling medallion.  Most people would just put on ceiling medallion and not worry about the sealing behind it.

Intermediate to the two pictures above, I could have taken a picture when I used wood glue to glue in a 5/8" dowel into the big hole.  I glued that in place on Saturday.  It fit nicely at a slight angle, so I didn't need to use any tape to hold it in place.  After doing that gluing, I did a first pass at sealing all the other gaps around the box, then after 24 hours to let the glue dry, on Sunday I sealed the big gap with the dowel in place, and I resealed a few places where holes or depressions had appeared in the caulking. Before sealing the big gap, I tapped on the dowel to make sure it was being held firmly in place with the glue.  Here's a closeup of the big gap after sealing, note that you can't see the dowel or anything underneath the caulk:

But now I notice that there may be air blowing through the small holes in the electrical box itself.  It looks like the box is screwed down to a wood joist, but apparently that doesn't seal it perfectly.  Now I need to investigate how I could seal the holes in the electrical box.  I don't think caulk can be used, as only materials approved by an electrical authority can be used inside a box.  I was thinking I could cut some of these outlets sealing (so they say) foam pads to small circles and stuff them into those holes.

The ceiling box is particularly important from a sealing perspective because the spray foam insulation doesn't come all the way down to the ceiling sheetrock to prevent airflow and mixing.  My attic is not very large (you couldn't actually store much stuff there even if it was open, I don't even think a single row of bankers boxes would fit down the center line under the roof peak), but there is almost a foot or so of free air space (note that the attic is by design a unvented attic enabled by the use of closed and open cell spray foam under the roof deck...this was a very expensive approach).  VOC's can accumulate in that free air space from any part of the attic foam, mix within the free air space, and then flow down into the room if there are any unsealed gaps.

In vented attics, the sealing between attic and living space would be even more important because a vented attic can exceed 140 degrees in summer.  My highly insulated attic should not deviate that much from room temperature, in fact from a thermal standpoint I could remove the entire ceiling, but I'm still worried about the VOC's blowing from attic into room.