Search API / Facet API hierarchy based on taxonomy term reference across vocabularies
One alternative, which is not quite the same, is to use dependencies between facets.

So, the product families facet is shown only if a supplier is chosen. And the product series facet is shown only if a product family is chosen.

With hook_block_view_alter() one can rewrite the block title, so that the product family facet block says e.g. "Acme product family", if "Acme" is chosen as a supplier.

Again, this is not quite the same. But it provides an acceptable user experience, I would say. And it might be a suitable solution for some visitors of this question.