In English we do indeed use curdle for blood, but not after it's left our veins. Bloodcurdling is an adjective we use to mean "very frightening" and we could also say things like "My blood curdled at the sound of the scream" to mean that we were very scared by the sound. However, the blood has to be still inside us for that!
Blood can't really coalesce; that's about separate things mixing/blending. Blood is just one thing. Broken bones could perhaps coalesce, although it doesn't sound very natural to say. I'm not sure wounds could, because the flesh, even when torn, is still one thing.
Blood doesn't freeze outside of the body (unless you are somewhere exceptionally cold, of course!) but we do say non-literally things like: "The blood froze in my veins" with a similar meaning of being frightened or shocked as in the above example for curdle.
Broken bones can fuse , and I've also heard people describe them as "re-fusing" in the sense of "fusing back together again".
Wounds wouldn't harden, and it doesn't sound very natural for blood, although I suppose that blood does do actually it.
I don't like jell for blood either as the link to jelly is not a pleasant mental image!
Solidify is good for blood, not for wounds!
We use stiffen to talk about what happens to the flesh of dead bodies (rigor mortis) so I'd avoid it for blood or wounds because of that.
Thicken is a nice term for blood; it is much better than stiffen for any liquid. It's only a stage in the process, however - first blood thickens, then it solidifies.