As of commit e4954e432e972b2f763911245bafae6bd611e99c, updateability is partially supported.
[x] New closed ways are written to the areas table even if not all nodes are present in the diff file
[x] New multipolygon relations are written to the areas table even if not all member ways and their
nodes are present in the diff file. Missing member ways are retrieved from the slim tables.
[ ] Changes to the locations of nodes don't trigger area updates.
[ ] Changes to the ways don't trigger updates of areas derived from multipolgon relations.
Cerepso should support areas and store them as Polygons/MultiPolygons.