no matter whether buildings have natural or 'manmade' structures above, there are pockets where is rains in doors, this is consistent whenever the rain event is active (and always initiated by sleep). see screen shots for example
Environment
Java snapshot 20w20b
Linked issues
Attachments
Comments 2
See MC-179845 for a fix.
Your world is broken by the 20w17a snapshot and needs to be fixed manually.