The impact of a devaluation of the national currency under a fixed exchange rate system
This looks good assuming that your country is a small country (i.e., the change in the domestic demand of foreign assets does not change the interest rate in the foreign country). To be clear on the full story, at point A, we have that the foreigners want domestic assets, and so that's why foreigners demand more domestic currency, and that's why (as you said) the Central Bank has to counteract by buying up foreign currency.