This feature would allow us to make sure that the translation for a certain term appears the same number of times in the target segment as the source term does in the source segment (make sure that there is no potential inadvertent omission).
Source: This contract will ...., and it must be stated in this contract.
In this case, the translation for "contract" should appear twice in the target segment unless either is intentionally replaced by the pronoun or otherwise omitted.
Aren't there cases where the 2nd appearance is replaced by a pronoun? I prefer to keep thing simple and do this rather (not quite) often.
But I see the advantage for longer segments. Maybe an optionally displayed number (superscript or better subscript) can be of help here when appearance > 1, with a different color when numbers are not matching.