except the pre-included pictures are not the same ?

Maybe I am dumb, but I cannot find a way to upload pics. I got one in, but it was accidental. I have no idea how it happened. I understand the limits.

What's the meaning of the different "Picture Completed" medals pictures get when you beat them? There are multiple designs for them. At first I thought they are related to the highest difficulty you've beat a puzzle, but now I've beat two 100-pieces puzzles and one has a gold medal and the other one a silver one. Are they tied to completion times, like is there a hidden clock running in the background? Are there even higher tier medals than the gold star medal one? I'm confused....

这个游戏如何添加自己喜欢的图片在游戏内打开？

getting this error when loading https://pastebin.com/PhNjvc1T but considering the lack of activity on steam for this game I'm not hopeful for a solution