Do local taxes help in paying back foreign debts?
If you actually raise local tax it would help you can just convert the money raised with local tax into the currency in which the debt is. For example, if UK has some debt in Euros they can raise taxes in pounds and just exchange them at an exchange rate for euros and pay down their euro denominated debt.

However, it would not be possible to pay the foreign debt by just printing the local currency as that would lead to depreciation of local currency and hence its exchange rate.