I’m not sure I understand the question. Historically, the European African wars have mostly been the opposite of costly (at least for the Europeans), as they colonized the the continent, and tapped into its vast resources. The costly wars have been Europeans putting down African unrest, and then after independence, getting involved in humanitarian efforts, which have been extremely costly.
Are you wondering whether China will pay a heavy cost if it attacks Japan, in light of its great wealth? Well, this depends a lot on whether they win. As I understand, these islands have a vast gas reserve underneath them, and the political capital for the Chinese government in the event of a victory would be incalculable.
If they lose however (which is very possible because Japan is under US treaty protection), the costs would be enormous. China would have lost yet another war, further eroding their military record, the regime would suffer further illegitimacy, and the financial cost of the Chinese navy would be very large I’m sure. Remember, when Argentina lost a war over some resource-rich islands, the military junta collapsed almost overnight. People don’t like it when they lose wars.
I think China will lose any war with Japan. I think Japan has so much up its sleeves we would be astonished. At the same time we would help and fight it as well.
About an African war, I just meant, and I am not well read on it, it seems a lot of Europe’s (Britain’s) have been drained in Africa fighting uprising (Zulu, Mahdist wars).
At the same time, I think if we want to fight China we need to destroy their African farm’s/ranches/mines.