I stood for 3 months at Mariana's apartment and could have stayed longer easily. The more you get to know the city, the more you understand its fantastic location.
Roma Sur is at walking distance from Roma Norte, Condesa (just across the main avenue in front), Narvarte and if you like to walk, you get to Reforma without much effort.
Roma Sur can have a local vibe without being too much touristy.
It's perfectly safe even by night, has everything you may need such as supermarkets, bars, a wide range of restaurants, a local market (Medellin) and it's served with public transportation like the Metrobus right across the street.
Mariana and the neighbors are kind, warm, and makes you feel at home.
Mariana was always there when needed, but there wasn't much to sort out because everything was ok.
I absolutely recommend her place and I already miss it.
Cdmx is a fantastic city and has nothing to do with the news I hear back home, of course you have to practice some caution like any other place, but you'll be more than ok here.