Do you have a picture of the block or finished size or is it a mystery?
Ok, so the old math to figuring out a triangle is finished plus 7/8ths. That was my guess on why the blocks would finish at 4" and 2".
Are you making one or two sets out of that, that is are you sewing once along the diagonal, and cutting off a smaller bit, or are you cutting the squares in half, meaning you would sew two equal sets.
Is this a pattern where it is exact, or will you be cutting down? There are tiny differences between the reality sometimes when we are using the diagonal measurement or the horizontal measurement as our standard. So I would cut both oversized and trim down myself.