An agreement on currency valuations between major central banks is unlikely to affect US trade deficits. Such a deal would have to include smaller players like Mexico that have far less control over exchange rates than the likes of Japan or Europe.

The trade deficit with China is also not likely to be affected since the US no longer makes many of the consumer goods it imports from China. The Yuan would have to appreciate far too much to induce US manufacturers to jump back into these markets.

I do see Trump trying to make another Plaza Accord for political reasons. It would demonstrate to his followers that he is doing something even if it is ineffective at resolving festering trade sores.