Roma is the story of Cleo through her eyes. I do think the earthquake and forest fire scenes symbolises her state of mind. It shows all the turmoil in her life and and that she doesn't have a bit control over them.
However there's another aspect of the movie.
Roma is basically the memoir of its director, Alfonso Cuarón's own childhood and his city. He said ...
The word tselina (no soft consonants as normal) means "celery" in Bulgarian. You don't need to look for metaphorical connections in other languages: given that we see this written on a greenhouse, it's pretty safe to assume that the only significance it has is to denote what's growing in there.