Saturation and Instant Health/Damage effects don't have an icon

Confirmed.

This is probably intended, as it is supposed to be a short duration effect, similar to instant health and damage effects which do not have icons either.

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Confirmed for 13w49a.

Resolved in 14w29b. (but their are some pretty quirky bugs with Saturation that I don't understand)

Affects 18w43a, which is problematic due to Saturation being a survival-obtainable status effect

that said, blue orchid / dandelion suspicious stew will probably only give saturation for one tick in the future

Affects 19w11b

They were never meant to have an icon.

Yes they were.