Logically, the sizes did look wrong.
There are 2 smaller triangles making a half triangle connected to one larger triangle to make a block. The 2 smaller triangles are cut from the 4 1/2" block. When you put that triangle next to the triangle cut from the 3 7/8" block, that 3 7/8" triangle is smaller. Would it be easier to stitch the triangles aligned on the center point and trim off the edges of the larger one after sewing the seam?
This is actually a border - sewing by their instructions made the border way too long. Squaring up to 3 7/8" did fit.
I have trouble with points anyway, but when one comes out 1/4" different (too long on one side,) that isn't me. (Except for trimming wrong)
All the instructions said was to trim off the ears. I think there was a misprint.