Not really, the same sentence with “robić” (or “zrobić”) as the verb would not be very natural.
But anyway, I’m not really sure if the current “Moglibyśmy trafić gorzej.” is the best translation for “We could do worse.”
The use of the verb “trafić” suggests that the speaker was faced with some random event, and got an outcome that was not-so-bad. For example, they might have got a pretty average seat on a plane, or a merely adequate teacher in their evening class. They’re not very satisfied with what they ended up with, but “it could be worse”—they can’t really say they got the short end of the stick.
“We could do worse” in English seems to have a wider range of potential meanings. To me, it sounds like it could refer to the speaker’s own performance in some task (maybe they got an average score in a test) just as well as a random event (like the ones with the plane or the teacher). Please correct me if I’m wrong.
The verb “trafić” itself can mean a few things depending on the context. Here’s a quick translation of the most likely meanings listed in the Polish Wiktionary (https://pl.wiktionary.org/wiki/trafić):
- hit a target
- find the way to a specific place
- come across something or somebody
- turn up somewhere by accident
- get something by accident
- choose something by accident
The last three provide a pretty good clue when it comes to interpreting “trafić” in the context of this sentence.