I think that piece of hickory should be fine. Yes, there is some grain run off, but that is really minor and should not be a problem. The grain is straight enough and nicely quartersawn - hickory should be able to handle that just fine. That heartwood should also not be a problem. It's been reported that the heartwood is slightly weaker than the sapwood, but it's still plenty strong enough.
You need to be careful on prepping the glue surfaces. Those black markings on the hickory, created by the friction of the circular saw, must be removed prior to gluing. I prefer to clamp the backing down onto a flat work bench. I then use a sanding block with 80 grit sandpaper and press it down firmly. Use LONG strokes with even, hard, pressure. It takes only three minutes to prep the hickory lam that way.
I'm wondering where you got that hickory from. Fairbow maybe? I just like to know. You could try to show the supplier of the hickory these pictures and see what they got to say. I seriously doubt it will be your fault; that crack is a flaw in the backing. They might offer you a new one for free? Also, try to find out if the new hickory backing is cut from the same board/tree as the other one. Perhaps there was something wrong with that tree/board, such as ring shake.
In case you're looking for a replacement of that hickory, I'm pretty sure both bamboo and ash would do fine. The maple is a bit more tricky I think. However, creating a nice flat backing lam is of course a lot more complicated than just buying a flat backing lam. If you have a decent table saw, it's not a big issue, but with only hand tools it's going to be difficult. I can offer you a white oak backing lam (perfect grain), or a strip of bamboo, at low cost if you're interested. Shipping such a long item might be difficult, even within our country, but I could cut it in half so you can put a splice in the handle. But I'm pretty confident that this new hickory backing will salvage this bow.
Jorik
