Taking on some of the things both Calandro and Splododyne have mentioned, I have come up with these results.
Added light portals in the openings of the ceiling for the large lights.
Removed the light portals added in Render 06.
Changed the strength of the emission shader of the larger lights from 10 to 50.
Replaced the emission material light with an area light set to 100 W.
(Switching the material on the now unused light, to a diffuse shader)
As Calandro had mentioned again about using light portals, in Render 06 I added a light portal under each of the openings for the large lights. When comparing Render 05 to Render 06 though, there didn’t end up being much of a difference when I used the light portals in this way.
With Render 07 I thought about what Calandro mentioned about the framed node group in the material for the large lights that is perhaps redundant to have. I wondered what would happen if I increased the emission strength. Would that have an affect on the amount of noise around where those lights are? To my surprise, it did not all that much compared to Render 05 / 06, though I’m not sure why.
In any case, I also tried out the first half of what Splododyne suggested. Increasing the max bounces for the Total and / or for the Diffuse bounces did not affect the render all too much. I tried at most upping the Total to 24 and the Diffuse to 12, I wasn’t sure if upping them much more would be an optimal option.
I also looked into that Light Threshold option that Splododyne mentioned which I found located under; Render Properties->Sampling->Advanced->Light Threshold. Lowering it further or disabling it didn’t seem to affect things much.
Finally, for Render 08 I added an area light (as Calandro suggested) just in front of the large light (for context those large lights are instanced) and replaced the emission shader that I had for the large lights with a diffuse shader.
This works, though I’m not too sure why the resulting render is quite so different. Is this something that would make sense to happen when adding area lights into this scene?
I have a thought that this might have something to do with the glass shader’s light path node not accounting for the area lights (since the rendered result is similar to Render 00). Though I’m not sure if that’s the case.