We need the ability to fail a goal rather than leave it incomplete. Failure is just as important.

I agree. Failure should not be a stigma. Starting and trying at all should be awarded even if you fail.

Only those who dare to fail greatly can ever achieve greatly

Absolutely! You can update the text in the goal as a fix in between.

100%. Moreover, the fact of finishing something is also very important. Incompleting remains you with the feeling even worse that failure.