Good question. I could not for the life of my figure out how to get historical reward data using the Condenser API or even BEEM API. There's no examples out there and the documentation is frankly abysmal.
A SQL query did the trick and it's a one-liner, so is very quick. You can run HIVE-SQL queries from Python and extract the results into variables.
Ah okay, that makes sense. I found that HIVESQL is easier to pull info anyway.