I think the person who added the hybrid formula name just didn’t specify the variety. I edited the hybrid formula.
We try to be as specific as possible with plants because there is a tendency for infraspecifics to gain momentum into becoming full species. I’m not familiar with your goose example so I can’t say how it compares, but hybrids in plants involving infraspecifics tend to be more significant than one might expect due to the aforementioned momentum. If you want to see some funny hybrid formulae, search Asplenium trichomanes, which contains a bunch of cryptic speciated lineages that all hybridize with each other and most other sympatric Asplenium. 40 taxa for the price of one species search!