I agree it probably makes sense for the map to use UN recognized names of the time for times the UN was around and had recognized names for. Whether or not it's the absolute best answer in a given situation... it at least provides a definitive source to defer to for the modern period where the most debates might come from. For more historic names other methods need to be used and blended to the modern names which is sure to be a treat of user debate :).
"Northern" was added to the name in 2019, before it was just Republic of Macedonia.
> "The Prespa agreement of June 2018 saw the country change its name to the "Republic of North Macedonia" eight months later." - https://en.wikipedia.org/wiki/North_Macedonia