Absolutely you can do it programmatically - and that is in fact what my LLM does for me: (a) when new CSV format is encountered it writes a beancount importer to handle that specific file format, and (b) intelligently understands the descriptions to categorize the entry and update that rule in the categorize.py script if it doesn't exist (so PHO/GRILL it understands is a restaurant, etc)

Those are generally one-time task. However the real use is being able to chat with the LLM about hypotheticals....ways to become more tax-efficient, etc.