can we say 'ett misslyckande är nog'??
It'd be perfectly understandable to a Swede.
Ok, so failure is bigger than mistake. Did not realize there even was this misslyckande available... Thought a big mistake is a failure. I think even epic mistakes can be Made. But I am not English after all.
Failure in English generally means a total lack of success. A mistake is just an error and one or many mistakes can ultimately lead to a failure.
Would the structure "Det är nog med" work here...?