fall short of the mark; miss the target; not up to par
Used to describe something that fails to meet a standard, expectation, or goal. Often appears in negative form 的に達しない.
His proposal falls short of the mark.
This translation still misses the target.
The phrase combines 的 (mark, target) with 達しない (negative form of 達する, to reach). The exact historical derivation is uncertain, but it is a straightforward compound expressing failure to reach a target.