Important Validating user input is also important for security.
Therefore, you also have to make sure that the values that users enter can be correctly converted to the appropriate data types.
Avoid all the anomaly, let user input in any format they like but always change entered date into 'dd-mmm-yyyy` format. Yet, I am aware that the above is a very simplistic (as mentioned before) approach and does not cover many cases.
Excel can recognize the localized format and change them to your preferred format accordingly.
You might also have certain restrictions on the values.
Even if users correctly enter an integer, for example, you might need to make sure that the value falls within a certain range.