The "solution" in this case is to use Scenhack to "change" those units to their current version and when that is done and saved the scenario will report the correct range that can be used even though the correct range is what is currently being used.. just being reported incorrectly
However, as the original scenario's mortar ranges would have allowed use onto Japanese positions and the reduced range does not I have redeployed those units closer to the lead units to compensate