Aside from all that, basically, if "rivers turn to blood" when HFS is unsealed, then it raises some serious questions about the nature of this whole thing...
If the "evil" in HFS is just the clowns, then it makes some sense - the evil creatures were just sealed away in a boring and inhospitable wasteland.
More to the point, though, if you release HFS, and are alive for long enough for this "evil" to corrupt the world, then it means that either A) You killed all the clowns from at least the initial surge, and are holding the tides of Hell back by either force of arms from your elite team of demon-hunters, or through a massive mechanical doom machine destroying any creature that pokes its head up, or B) that you re-sealed the HFS. Either case, it means that there's no clowns frolicking around in your fortress, and it means that it's not the clowns that are the source of "evil".
If HFS is actually the source of all this "evil", then it raises some questions about why there are demons walking around the land (showing they escaped) without destroying the whole world with the leaking Fisher King "evil" all around.
If the lion's share of the "evil" in the world was bottled up, where did all the "good" come from? Why aren't they doing anything, letting the world get taken over? I mean, if there are gods, even not particularly good ones, why do they take no part in the world while it goes to shit because the clowns are partying all day?
I mean, it's kind of silly to have a mechanic for "the world dies, and there's nothing you can do about it" in a game, espeically in a game where you're pretty much supposed to Dig Too Deep. There should be a way to Fight The Power, and frankly, demon genocide is the most logical way to do that.
So what, if you start to make the clowns go extinct, does this crap reverse? Do the rivers flow with fermented ambrosia rum, and the world turns into dwarfy paradise?