training threshold

There's lot of puzzles, where a clearly winning move fails, only because of some "silicon-mate-in-5", which makes the training quite frustrating. I think, there should be some threshold letting me to keep on finding THE best move.

Puzzle failing move often leads to position, from which I can beat the stockfish 8 without much thinking, which makes failing the puzzle absurd.

Absolutely - chesstempo uses a threshold of +1.75 for alternate moves and does not have this problem. lichess needs something similar.

whats the threshold for your frustration?

quite a lot of puzzles i played have acceptance of "Good Moves" and i don't mind failing a puzzle, because i clicked "Training" so i want to learn something and there was no puzzle yet where i didn't learn.
Rating is a 4 digit number on a computer screen.

I was annoyed by this at first but I came to like it. When you find a good move, you need to think a bit more to see if there isn't a better one.