Those small pin knots shouldn't be a problem. They are near the handle, and with the larger one, there is still a little wood left between it and the edge of your bow. I would probably go ahead and back it with linen or sinew simply because I always back my bows. Ideally, if you had seen those knots earlier it would have been a good idea to have left a couple growth rings over the knots.
It really shouldn't be a problem. My first osage bow I literally de-crowned a big knot 2/3 of the way down the limb. After learning that was a no-no with osage, and not wanting to remove another 2 or 3 rings, I glued 2 linen patches over it, then put linen over the entire back. No problems at all, and it shoots bullets. Good luck