Hi, organizers,
Thank you for your exciting puzzles!

I guess there is another answer in the upper left of 19.Triangular Dissection.

In the answer, I think (1,1) and (2,2) are connected,

but isn't it allowed as another answer in which (1,3) and (4,1) are connected instead of (1,1) and (2,2)?

I have a similar question for #21. I was marked wrong for the answer [45,4694,55] and the submission log says the 69 is incorrect. I have those middle two dots (at (1,5) and (5,5)) connected, and it looks like I could theoretically disconnect them and replace them with a line from (2,1) to (5,8) and get another potentially valid answer.

Is there a way to submit my completed grid to see if it might be an alternative solution?

Never mind, I found the error. :(

Hi moyam,
We are glad you are enjoying the puzzles. Thank you for bringing this to our attention.
Your note here is correct, and we have allowed the alternate solution as an acceptable key now. We will reach out to you and other affected participants soon to discuss options.