I wish there was a chapter that goes more into Mahiro's drawing skills because he's actually quite good that. I personally believe that he may not have tried drawing before (or gave up because he thought it wasn't good enough)
Miyuki and Kaguya, looking at this and realizing that they accidentally made Miko and Ishigami into themselves
"I want to make them confess first" is a good motivator sure, but it's not good romantic advice. The moment Miyuki gave up on this specific point was when he was able to confess to Kaguya
So Shirogane was already the council president when she she fell for him because he's wearing the thing, the scenes after are probably when he tried getting Kaguya to join the council