Invoicing/settlement currency is not the same as source of foreign currency. Net settlement of imbalances have to be done somehow.

And yea, China exported real goods and imported claims on foreigners/foreign assets/

If China sells goods, receives Dollars and then swaps it for gold, or just real assets in Africa then it still means the surplus is settled in foreign assets. If foreigners can't hold CNY assets, then adjustment happens by China holding foreign assets instead. Even if China holds 0 Treasuries, 0 USD assets and only real assets even then a trade surplus country like China is accumulating foreign assets, so the world is not holding financial claims on China, it's still the creditor and Yuan (a financial asset) isn't the asset the world is holding.

And look at what % of total trade is done in/swapped for real assets. I can't find the exact numbers but real assets are more complicated to obtain. Commodities tend to bubble up when you buy too much of it. Keep in mind they have over a trillion dollar trade surplus.

. If China stops recycling its surplus into the US bond market then the US loses its primary source of cheap credit.

Not how credit works, it is rest of the world's demand for US Dollars that results in US having a current account deficit, again rest of the world is willing to accept USD, US fiscal deficits are financed by spending itself. If China and the whole world decides they don't want Treasuries, US domestic holders can buy it instead, and if domestic people don't find yield attractive, the Fed can buy it. Or, Treasury can simply spend without providing free money assets i.e. Treasuries. The real adjustment wouldn't US can't 'finance itself' or whatever but shows up in exchange rates, as I said, Americans will have less foreign goods. And Trump has already done a light version of that with his tariffs.