So, China loans the money, which returns to China via Chinese construction companies
This is par for the course in international assistance, not specific to China. Not limited to development assistance, either; most famously, US military aid to many countries around the world is earmarked for spending on US weapons firms.
Also relevant: the Palantirs are linked to Sauron, and anyone who uses one is almost certain to get corrupted and dominated by the Dark Lord.