This would not meet most building codes. There is no fall protecting within the railing. Most jurisdictions will require no opening large enough to allow a 4" sphere to pass through. Many people put up temporary barriers or entire railings to pass inspection and replace them with something more open once the inspection is passed. The time when this may cause an issue, other than someone falling through it, is when the house is sold, the bank may require the railings to be brought up to code before the sale can be completed.

There are finished veneered plywood panels that attach to small hole in the uprights. We put them up is we are having a party with two year olds - or inspectors.