How about no? If that's all you have to say then I DGAF. I swear when encountering something ridiculous, you want to me swear less? Explain it so it's not ridiculous.
On a serious note, well it seems the girls are aware of the ghost, Koume saw it first, Tsukiko said that apartment building was built on top of Majin's burned down house, she is aware of it and didn't want to enter before, now she is teasing that she might enter, An is just so easy going that in contrast to Kiriya who freaked out, she is just like "Oh, that's Tomoko's ghost, cool let's play". She also spent a while at Tsukiko's place playing with Koume, it's easy to imagine Koume mentioning it. It really is just that.