Encore CS6 is definitely older, but I used it to author the Hybrid v2 DVD three years ago and I’m almost positive I had Windows 10 at the time. So it’s possible it could still work.
Personally, I’m of the opinion that if they no longer support it or offer a way to purchase it, it should be fair game to download by whatever means.
Yeah I’d probably go that route. IMO encore was always consistent with creating the best menus.