Buying Up the Planet: Out-of-Control Central Banks on a Corporate Buying Spree

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2. CURRENCY DEVALUATION is a brake

If Norway simply prints extra currency to buy foreign assets then their currency will decline in value. That will make their purchases more costly and will cause inflation. The target nation can benefit - China is not likely to harm the US economy if they own parts of it.
The federal reserve posts its audited financial statements in case you want to see how much they have invested. The fed opposes congressional audits to protect itself from politicians, but they don't mind independent auditors auditing them.