It's a bit tasteless, I have to agree. You have to stick with the theme you set up one way or another, or the game's going to end up a mess of completely different themes with no red line to unify them all.
How do you fix a bunch of burning pigs running about? I don't think just making them lie about and screaming in agony is going to help all that much. Maybe they managed to find a way to completely block out the pain after a while, being accomplished wizards on their own? Maybe they've accustomed to their lives as pigs, but can't find a proper farm because they're *ahem* on fire?
They wouldn't be all that bummed about the immortality either, of course. One possible way to fix it would be to involve these pigs with the story a bit more seriously. Not just have them act as slightly more interesting environment props. I mean these guys are *old*! They MUST know something that would help in the main plot.
You just have to start from the beginning, and ask yourself as you move up why these things are happening, and make sure they make sense in the game world. Braccus Rex is an asshole with a lot of power, he doesn't really need motivation for doing these things. So let's say he dislikes some dudes and turns them into pigs, then makes it so they can't age or die by fire, and sets them on fire for all eternity to torture them. Cruel, evil, sure, I like it.
So how would these mages-turned-pigs react? When you are in incredible pain, you can't think properly. I doubt they would know things about the world, and I feel that most would have killed themselves, because when you are in disabling pain all you can think of is how to end it. I imagine if one of the pigs were to overcome the urge to end the pain through suicide, then they would have to be immobile, not running around, as these pigs haven't been able to sleep for years and shouldn't have the energy to move their bodies or even speak when you talk to them with pet pal. And I was wrong about the screaming and writhing, because with no energy they shouldn't be doing those things either.
And people will tell me I need to calm down and it's just a game, not real life. But please realize I'm not basing this on my own tastes, I'm basing this on the world that the story is building. In this world things are grim and shitty things happen for indiscernible reason, and there is some semblance of realism. In this world you would find an immobile pig on fire, just lying there on it's side, with dead pigs all around it. And pet pal wouldn't reveal any info. After curing it speaking to it would only observe that it was asleep, until time had passed and then you could finally learn the awful story of why this happened. (with pet pal I assume, I don't know if there is a way to turn them into humans again I haven't gotten that far)