Sorry, but you won’t get this new feature in GS 7.
In order to download the list of available rate table, we need to integrate with a completely new suite of API calls eBay introduced in the last year or so, which use a different authorization flow, a different authorization token, and a different way of communicating with eBay’s server.
So it’s quite a lot work, and we won’t have it done before GarageSale 8.2 ships.