I think keeping Kellie off the defense team is s good call for the exact reason you stated. If your defense color end up 2-2-1 offense will have an easier time.
Is your alliance running red only for center?
At your progression Kashrek would be a pretty solid tank as well. Do you have any blue 4* ? Rainbow is usually ideal but in very early stages your 2 4* green at 3-60 is good. Is Wu your only yellow?
The 2nd team looks good. A lot of heals but at that power level opponents will struggle. Wilbur not heals but is support. Sabina and caedmon remove the benefiy wilbur grants opp. Looks good