I think they are unrelated.

The Carthaginian inactivity is a clearly a bug - I think specific to the islands geography and/or naval AI. It bothered me before, but given that we are moving on their homeground, we can probably ignore it. (Although personally, I think the second Consular army going south should expell the invaders from the islands first, just for roleplaying reasons.)

Iberia not attacking us need not be a bug. It's arguably a smart move on their part - IIRC they are not as strong as Seleucia or Egypt, and we actually have pretty decent armies near them. It will be interesting to see what they do. I wonder if they will strike if they wander near a powerly defended province? (I suspect a weak border defence may trigger war - it did in MTW, IIRC). Remember Macedon "menaced" us a lot during FLYdude's first half term, before ultimately making an opportunistic attack on a weakly held settlement.