The cast aluminum grill on the Elf, also has a slight twist to it, and I tried for quite
some time to tweak things. I just couldn't get the hood to fit to it nicely, and have good
looking seams, so I "made alterations as necessary". I added a small pie shaped
piece to the side of the hood, on one side.
Got a woodburner in that tractor mansion of yours? Lay the grill on top and prop the corners to where you want them to end up. Apply weight to the corners and wait for spring. It'll gradually straighten out a bit every time the stove gets hot.
I do my cast aluminum griddle every few years like that. It goes wonky with use until one corner is about a 1/2" higher than the other 3. The griddle takes about 25 lb of weight and about 1.5 months to straighten out with normal fire in my small airtight. Your grill will probably need more weight because it's thicker.