No, Food52. No. Whatever this menu you posted is, it is not a 'medieval feast.'
I'm trying to be fair here. I know they're trying to promote recipes on the Food52 web site. It looks like a nice menu. The recipes look delicious. Had it just been presented as a dinner party menu, I would have applauded the thoughtful combination of dishes and moved on.
But they called it a 'mediaeval feast,' with roasted potatoes and a cake for dessert. As we all know, there were no potatoes in mediaeval Europe. Nor was there baking powder. It's possible that onion confit existed in some form, but I've read most of the major European cookbooks from the Middle Ages and don't remember seeing anything like that.
And that's really what brings out the pedant in me. It's not just the history. It's that mediaeval cuisine is a distinct thing, just as Indian or Chinese cuisine are distinct things. There were mediaeval aesthetics, mediaeval theories of health and nutrition, and regional tastes underpinning that cuisine, just as there are Chinese aesthetics, theories of health and nutrition, and regional tastes underpinning Chinese cuisine.
You wouldn't make a fish stew with supermarket-grade curry powder, apples, and north Atlantic cod and call it Indian. Indeed, I suspect if you tried, you would be soundly thrashed for it, and rightly so, as it doesn't reflect the Indian culinary aesthetic at all. The chickpea soup that opens the 'mediaeval feast' is a beautiful thing, but it doesn't reflect the mediaeval culinary aesthetic.
There is a large and very accessible body of research into mediaeval foodways and cooking, both in print and on the web. Medieval Cookery is one very good online resource, and if you Google the phrase 'medieval recipes,' your first two search hits will be links to it. It would have been great to see a major food site take a thoughtful look at historic cooking. It's not surprising, but still disappointing, that they didn't.