I think you may be second guessing your self/overthinking this block :wink: :D Not many would venture to try lining up stripes... I would make these blocks and would add a sashing strip...they would be separated and the fact that the stripes don't line up would not be noticed... I would use a more solid colored fabric for these.
This block with the stripes landing in different places will make the quilt have more movement, which is very desireable.
Please keep going with this...it is going to be an amazing quilt!!! :D :D :D
I agree with starching your fabric pretty heavily...you will be amazed at how well the triangles will behave :wink:
Double check your 1/4 in seams...maybe a stack of post it notes to use as a guide for your fabric will help with your seams/piecing. You are not that far off to having perfect points!!! :wink: