Let’s put it bluntly: current stockpile filters are inadequate/inappropriate.
The primary reason being: they seems to be put together hastily using the entity categories as groups etc.
Why is that bad? because stockpiles should be categorized by USE, not entity taxonomy.
e.g. “plant” category consists of fiber and herbs, without a way to properly separate them and allocate dedicated supply (so it is possible that one type which is more abundant will eventually use up all storage). Also, the location they are used may also be different. Putting stockpiles at each location and end up having the “wrong” type of plant resources will be a common problem.
Suggestions (mutually exclusive)
redo all stockpile groupings so that they are based on use. not taxonomy. The designer for this probably has to know gaming habits of all players to provide a good middle case that will serve most people.
simply put all existing possibilities into one big UI. (e.g. use some external script to parse all entity json and collect their categories etc and generate the stockpile ui automatically with each build, instead of having to manually maintaining it) to allow finest possible control as a workaround. Groups can still be there for those who doesn’t want fine-grain control (which can potentially be auto-parsed as well).
add in-game customizable filter using some expression language (predicate for storage candidates) instead of a simplistic tag/category method. (most flexible, but also most complex to implement, process and to use. most unlikely I think.)