Nice to get a flashback to Kumugi’s past. It seemed she always wanted to prove herself to her talented big sister. Sadly, one accident riddled Kumugi with guilt. As that eyepatch is a reminder of the incident. In fact, her wanting but being unable to say she was doing medical magic was because of that guilt. At the very least, Kumugi looks to finally be speaking up for herself.
Spica is a tough character to figure out because her pointing out the eyepatch means she must know how Kumugi would react. Still, she doesn’t seem like a terrible older sister, as she got her away from bullies and put her in the research club. Though it could be part of the image of the Harvest family and her likely being the head child of it.