Cross-Platform Compatibility is probably the most useless upgrade among the T5 upgrades.
Mortars are best used on defense missions, but further aren't even utilized for this inclusive perk.
Rarely is mortar turrets are taken. Rarely does anyone ever utilize the bonus this upgrade does. And honestly think it needs to be changed for something else more beneficial.
Here's what I suggest.
Change the upgrade to apply to all turrets. That way, any turret you bring into a mission, you can mostly direct to firing on specific targets. This will make the upgrade actually way more useful because it is pretty common for someone to bring turrets. And often or not, those turrets end up targeting the wrong thing.
If anything needs a change - It's this upgrade.