I think it can be more efficient for two-step RAG so you can reuse the natural language query directly, but for agentic RAG it might indeed be overkill.
Also, depending on the ingredient, it makes more sense to use cups as a measurement of volume, not mass, when converting to metric. E.g. liquids, yoghurt etc.
Another thing: although not strictly metric, but European recipes also use tablespoon and teaspoon as measurements for smaller volumes, so no need to convert this.
Just my two cents, other than that very nice work!!
As someone who already thinks very little of people throwing their cigarette butts out of the window, I would not want to set an example that littering is acceptable to my own kids.