Edit: the Nitwit was trying to access where his old bed used to be, allowing him to sleep in it and then breaking it caused him to find a new one. The librarian, who was transported from a different village, still follows the same behavior of walking in an out of a bedless building all night, It is possible that the villager i transported still sees his bed over 200 blocks away as his and wants to get there but cannot and so enters into the building closest to it

Villagers aren't sleeping in beds accessible to them. when given an building with 6 rooms with beds (see image for room dimensions/ layout). they would rather leave and stand in the bakery room that has no beds in the building and neither have a profession block in that building ( Nitwit and librarian)

in either situation they continually exit and enter doors, occasionally going outside unless blocked from doing so

is there a required dimension for bedrooms?