Thank you for reporting this bug.
We will fix this by the next update :)
↓This is by design. If it causes any problems, we will change it.
1. Both players and enemies can attack through walls (if their reach extends through the wall). This does not apply to most projectiles and ranged attacks.
Also, the stomach medicine is a little hard to understand, so when the side quest starts, we will add the location where the event progresses to the minimap.