To be fair on candidates, CLI programs create technical debt the moment they're written.
A good answer that strikes a balance between size of data, latency and frequency requirements is a candidate who is able to show that they can choose the right tool that the next person will be comfortable with.
I remember replacing a CLI program built like Lego blocks. It was 90-100 LEGO blocks, written over the course of decades, in: Cobol; Fortran; C; Java; Bash; and Perl, and the Legos "connected" with environmental variables. Nobody wanted to touch it lest they break it. Sometimes it's possible to do things too smartly. Apache Spark runs locally (and via CLI).
A good answer that strikes a balance between size of data, latency and frequency requirements is a candidate who is able to show that they can choose the right tool that the next person will be comfortable with.