TBH, I've not seen many people sharing the same region name between different entities/collections in the examples/questions I've seen posted over past few years. Maybe the reason I've not seen them is cos it's possible to do that and it works out of the box, but I have doubts here.

Most of the eviction/expiration customizations I've seen have been for specific entity/collections in questions related to the eviction/expiration not being picked (e.g. in Wildfly, forgetting to add deployment and persistence unit)

Although the characteristics you mention could be desirable, you always have the possibility to set them per entity/collection and get on with it.