Hey @ericcheong!
I'm not sure there's a way to encode types into a CSV by nature of the file type itself. The program you're using might be able to infer column types but it will be passed as text. Have you had success importing other CSVs in a way that retains their column types?
Otherwise, a number of other people have used libraries like xlsx (SheetJS) to build richer exports, but it can take some extra coding. See, for instance, this example of someone using it to export dates.