That's a performance issue. It's because there's quite a bit of animation in that scene. There's a low-spec mode in the preferences for mobile, but it hasn't been implemented for tablets... For now, try using a PC or enabling low-spec mode on your mobile device.
Viewing post in I keep getting fatal errors on my tablet
The project is currently designed with flagship devices in mind.
The animation-heavy parts use a significant amount of memory, so a device’s RAM capacity is quite important.
At this point, my understanding of optimization methods has improved a lot, and it seems possible to optimize those scenes further. However, doing so would require rebuilding them almost from scratch to achieve the same visual results, so their modification priority is currently low.
As for the side stories, the gallery content unlocked through them includes one illustration for Gahel and one for Elred, one each.