Jane, IMO you can't rely on the foundation papers for the seams to line up. And that isn't just with these, it's with any you do because we're all human.
I have to to the "pin trick" where I put a straight pin through the matching point of the first piece and then bring in the second piece and place the pin through the matching point of the second piece. From there, I place straight pins to secure the two pieces, being careful not to shift them. It helps to hold them by the outer seam edge when placing the pins.
Now, here's an invaluable trick from Carol Doak. Take the pinned piece to your sewing machine and set your stitch length to a basting stitch (that's 6 on my machine). Take a couple stitches through the outer corners and any matching points. You'll just baste, lift your presser foot and pull the fabric to the next point, take a couple stitches and so on. When done, remove the pins and finger press the seam open. If your points match, go ahead and sew your final seam (removing the basting stitches when you're done). If they don't, it's easy to remove the basting stitches and try again to match your points.
I'm on the second block and it took me three tries to match my points, but with this method, it isn't too stressful.