I just thought of one more comment: have you tested the UI/UX when there are enough columns so that the modal must scroll? In that case, the actions adjacent to the data will also probably not work very well; i.e., I would not make the user horizontal scroll to access the actions. Meaning, I think you'll definitely want the actions separated from the data, so that the data scrolls while the actions remain fixed position.
Sorry I don't have more time to experiment with actual data types. I'm sure you can do a lot here too. I once dealt with an app that imported a CSV with geographic coords [lat,long]. During import validation, we showed a map to allow for correction / precise placement. That kind of richness would be great. To be validated with your market, of course.
Good luck!