this isn’t really a bug in iNaturalist.
the place screen is here:
https://www.inaturalist.org/places
https://www.inaturalist.org/places/search?utf8=✓&q=central+valley&commit=Search
https://www.inaturalist.org/places/central-valley--3
this is how i would search for Central Valley observations:
https://www.inaturalist.org/observations?place_id=66863
you might want to read these other threads:
https://forum.inaturalist.org/t/butte-county-bounding-box-incorrect/8034
https://forum.inaturalist.org/t/filter-location-united-states/8991
note what Google Maps brings back for “Central Valley, CA”:
