I generally wouldn't advise to nerf the weakest faction even further.
Theres a difference between fixing and nerfing. A unit should be fine with it's intended performance, not due to "bugs" or unintended mechanics (see how Flak HT is only "fine" because of landslide bug).
Since when is 5 seconds "instantly"? Thats less than the reload on multiple tanks. You can also keep it tagged as in combat by using infantry.
It has been a long time since then, but it happened that i button a JPIV with Guards, it cloak and dissapear away. Not sure if it works.
Cammo is broken. /Thread.
You could argue if that makes it a balanced unit or not (and here we go into another point regarding the performance of a unit due to it's vet1 ability)
PD: 5s to cloak is equal to it's RoF. That is why it can shoot, cloak and fire again. This changes at vet3.