I make bows with knots like this that fade in and out of stiffness all along the limb........and it's always a craps-shoot. Usually that extra stiffness, created by the extra thickness, gets me through, creating a stiff spot by itself that fades in and fades out of the rest of the bend in the limb. BUT! Sometimes, if it bends anyway, this happens. The cure WOULD have been extra width around the knot, or enough extra thickness so it can't break.
If you still have a lot of draw weight to reduce, then mark that area, stay out of it and leave it stiff. It it doesn't bend it won't break......unless it just blows suddenly.
The only ways I know to PATCH this kind of thing, or splint it are kind of ugly. Del said, "The only way to strengthen the back is to put an overlay about 1/8 - 3/16" over the knot area having taken out a loooong shallow flat curved scoop." That's it there. And I have the best luck just binding these on rather than messing with glue. You COULD shave that knot a LITTLE flatter, and get a scrap piece with an intact ring (just like you would have used for the back), about 3-4 inches long. I might heat this in the microwave, reflex it into a curve, like Del said, a "scoop", and then clamp and bind this splint down firmly with strong twine, which you then soak in glue.
Ugly but works.