There's a Presbyterian Church ON Av. Belgrano between Peru & Bolivar in what is technically Monserrat, but only two blocks from the Manzana de Las Luces or going the other way some people might call it "San Telmo", though it's not. (All of this is just about 3 to 5 blocks from the Plaza de Mayo in the middle of Buenos Aires.)
Don't know the language, just that it's Presby.
Suerte