Eiro casually walked around the Monster Village, taking in the scenery a bit. That was because it was basically one of the only few things that he could do. Walking around and casually looking at things didn't require a lot of mental capacity, which allowed Eiro to continue working on his Ancient Language Dictionary in his mental library.
It was multi-tasking at a basic level. If Eiro had to stop to hold a conversation with one of the village's monsters, he couldn't really continue working on the dictionary, so it wasn't really true multitasking. But it was still good enough, since the conversations with the monsters didn't particularly take up too much mental capacity. Like this, Eiro was able to briefly observe some more specific ways that the village had changed over time.