How does one report for US tax purposes the gain realized on the sale of foreign securities where the sale proceeds have never been repatriated but reinvested in other securities?

I understand that the sale of the foreign securities generates 2 types of gains/losses: (1) the gain/loss realized in the foreign currency and (2) the gain/loss that arises from translating the foreign currency back to USD.

My question is: Insofar as the sale proceeds have not been converted back into USD, does this imply that no foreign exchange gain/loss has been realized for tax purposes?

The fact that the proceeds were not converted to USD is irrelevant. The sale of the foreign securities results in a capital gain which MUST be reported as a taxable transaction irrespective of the currency in which the sale was transacted.