This is an important concern. Stucco will suck up moisture from your planting bed and transfer it into your walls. I've used a paint-on moisture barrier with a gravel drain next to some of our walls but I'm not sure if that is enough.

We have a short "submerged" stucco wall in the rear yard that I would like to address. Would a painted barrier plus building wrap plus tin be adequate for the long term?

As a landscape designer, I shriek DON'T DO THAT!

You have to have a permanent waterproof barrier or the water you apply to the bed will soak up into the stucco and make it fall off. You risk rotting the framing under the stucco and maybe even the drywall on the other side.

Can you make a raised planter that leaves a few inches between the planter and the wall?

You really don't want to do that! You need to keep the ground / mulch 4-6 " below the stucco. Otherwise the stucco will wick up any moisture over time. If you chose to do it any way, be prepared to spend $$$ ($10K - $20K) to do a major repair down the road!