I think the idea is that if you claim a foreign tax credit to reduce your US tax, and the foreign tax is later refunded, you need to adjust your US tax return accordingly.
I am not sure, but it seems like if you have excess foreign tax credits for that category and the refund in tax doesn’t cause your US tax to go up for the prior year, then you just file the Schedule C in the year of the refund, and you don’t need to amend the prior year. The Schedule C for the year of the refund would reduce the amount of the foreign tax credits being carried forward into the year.
On the other hand, if the adjustment from the refund would make it so your US tax increased in the prior year, you need to amend and pay the additional US tax for that year.