Does it support multiple Amazon regions / marketplaces?

No. You can only connect to one Amazon Region and Marketplace per WooCommerce site.

Supporting multiple regions and marketplaces simultaneously from a single site is something we’re considering for the future, but there are many challenges with that.

For example, every region and marketplace has different inventory levels for the same SKU but your WooCommerce product only has 1 stock level. Syncing the level with one marketplace that is out of stock would make the product unavailable to other marketplaces even if they had stock available.

For now, we recommend using International fulfillment with FBA from a single home region, or having 1 site per region to connect to unique Amazon Seller Central accounts.