Today, there are dozens of well known and well respected film awards. When Garbo and her peers began working in films, there were no Academy Awards, no New York Film Critics Awards, no National Board of Review Awards, no SAG, no Cannes, etcetera…
So, if Garbo and her films seem lacklustre in their received Awards, it's because they can't be compared to a Meryl Streep. Streep wins so many awards because there are so many more to win. Considering the time, Garbo and her films did relatively well. The first “Awards” I can find documentation for are the Photoplay magazine awards; and, the popular “Ten Best” lists. Garbo films did not win any of the Photoplay Medals (begun in 1920).