Back on 1.3.2 when vanished there was a buff that shows up saying you are vanished (like potions do). Is there any way to get that added back in 1.4.2 builds?

This is documented in the changelog.

Removed the "Invisible" effect that would let you know in the menu if you were vanished. It conflicts with ACTUAL invisibility potions.

You can check your status with /vanish check or /vanish list