The Pestalozzi is a German-Spanish program! Ambitious, though perhaps not what you want. It is also well regarded, small, and thus very very tough to get into unless you are the child of an alum. I tried very hard for 18 months to get my kids in there because we live in Belgrano, befriending a director of the school, speaking to the German Embassy (which subsidizes it), calling routinely and pointing out we are German citizens. I got a meeting and a school tour for all that! The waiting list process is very opaque, and we're still on it. So our kids will go to the Goethe in San Isidro - less convenient, but probably better.
For English/Spanish kindergarten, we were very happy with Boomerang in Palermo. We also like Sworn for primary school in Belgrano, better that BDS: smaller, more attention per kid, less snobby. It was our alternative to Goethe. PM me for contact details if you want.