As of now, this is not possible natively in QuickSight.
If you are worried about having the data duplicated in the dashboard you could just create the calculation on the dataset and then hide the column with the boolean, in this way there will be only one column with the value available.
Another option could be, if the data is on a database that support case statements, write a custom sql to transform the boolean for the Missed/Met string.
I will mark your original question as a feature request, if any of the solutions I mentioned work for you as a workarround, please mark this answer as a solution.