I received a promising email from support that says they're investigating a solution, which supposes that someone there is convinced this is an actual problem and we're not just crazy.
Specifically for my problematic download: the page has a web build of the game, with download links beneath. Support say: "Thank you for the report, we have narrowed down the issue as being related to the SharedArrayBuffer support that is enabled on the page for the browser version of the game. We’ll be looking into making some changes to resolve the issue in FireFox."