Even confining the discussion to Asia, the countries that would have to take part in it differ in many ways: current exchange rate regimes (hard peg, crawling peg, managed floating); degree of capital account liberalisation; stage of financial development; trade specialisation and position in the vertically integrated Asian manufacturing industry.
These differences make the determination of how best to achieve the desired result extremely tricky: How large should the appreciation be, and should it be uniform across surplus countries? Is it better to implement it gradually or through one large initial exchange rate realignment?