I really think you missed the mark on Janna's URF-specific changes this time. -8% shield strength is okay I guess though Orianna and Lulu get to keep their shield strengths and have permanent shields... Janna's still decays over time and is actually hard to keep up to any significant amount if not ranked up at the cost of her damage in the fast paced mode on URF.
That's not really the issue though I really think she should have gotten a buff to damage. Her ult does no damage, w low damage, and Q typically needs to b channeled to do damage. She really deserved the bard treatment (how he does 20% more damage and takes 10% less...???) Her ult is also weak because the heal is subpar when first available due to the healing nerfs. So she's good for a knock back on a 20 second cooldown against champions with 1 second cooldown dashes and 20 second cooldown flashes...?
I know she may not be the worst ARAM champ but I don't feel like she measures up to other supports in ARAM due to the above, and would like to see her buffed as she's one of my favorites. Keep the shield lowered, maybe even more so, but buff damage or perhaps a janna-specific buff that gives her free bonus move speed and thereby a stronger passive to incentivize an off-meta AS janna?