「一方、このあたりの者たちはどう教えていたかと言いますと、
みんなはビルボ(?) というのは前からずっとおかしかったけれど、
とうとう本当に気が触れて、行方不明になった、きっとどこの池か川にでも
はまりこみ、歳(都市?)に不安はないとはいえ、悲惨な死をとげたにえらいないなどと話しあうのでした」
「えらいない」 looks like a typo. Did you mean 「ちがいない」?
「どう教えていたかと言いますと」 is strange too.
"Meanwhile, the people in this neighborhood were talking that
Birubo was already eccentric from the beginning, but this time he was
really driven out of himself and got lost. Maybe he was trapped
by a river or pond or something, although he has no worry about his age,
he must have died miserably."