You are going to improve your spanish if you want to get the CPL in Argentina.
The CPL Ground course last 24 weeks from Mo to Fri, 4 to 5 hours per day.
The official language is Spanish so the Examiners are gonna take the check rides in Spanish.
Only International Airports have English ATC comms on request but most of the flying schools are located in domestic airports without ATC Controllers certified for English Comms.
The mayority of the flying schools in Buenos Aires are located at Moron domestic airport, 20 NM west of the down town. No english ATC.
There are many options, PSA, Rudder, Fly Tango, Flight Center, etc.
The courses are disign in Spanish but it si going to depend if there are available CFIIs with good english for helping you, most of the pilots in Argentina have the ICAO English level 4.
You can check the flying school at Neuquen International Airport. The airport is certified for English comms, very good weather all year around.