I am not sure I fully understand your situation -- what I get from your post is that (a) you have some unused foreign tax credit from past years; (b) you have foreign income from country A and country B; (c) you have paid taxes in country A and country B of which country B may have lower tax rate than the USA on the same income. Please confirm this is generally correct or correct my error.
In such a situation , and when filing US tax return, as long as you have foreign income, you can use accumulated foreign tax credit -- note that TurboTax will compute allowable foreign tax credit ( i.e. a credit against US taxes on the same income ) based on a ratio of foreign income to world income. Therefore I do not understand your question about "lower tax jurisdiction" because while there is a "kick-out" for high tax, the rest of taxes are treated the same i.e. there is no distinction between tax rates of jurisdictions ( except for above mentioned "high" ).
Hope this helps
