Thanks for the reply, though I am not sure why a larger number of defence forces should diminish the battle force of attacking troops. Or are you telling the algo is dynamic. If it's static then e.g. 1000 attack power should always kill the same number of defence points. If it's dynamic and the attack power depends upon / changes with the number of defence points (e.g number of defending troops) then any indication of attack / defence strength is rendered useless as it is unpredictable what the opponent will have. So in either case there should have been a better outcome than just the four javs/psilos killed.
In any case, capitals on my server are either 0 or 5 without troops or 20 with, as you say, millions of troops. So, which ever way you put it the capital challenge seems only to be for top players. I certainly won't waste any more troops on a capital challenge, in the same way that pantheons have been rendered useless.