But in your post you mentioned that Milestone bonuses haven't been considered. You might consider editing that and add another column for spend bases milestones.
Still I think 10% is a bit too much for amex. AFAIK on Plat travel you get total of 48K points on 4L spends. Considering the average value of 1 MR points= 60p, we get 7.2% value back. Now the forex charge on plat travel is 3.5%+GST the effective value back is 3%.