kartonage
The cutoff at 85°03'S is on purpose due to the generally used projection (EPSG:3857). So it's an artificial limit. See https://wiki.openstreetmap.org/wiki/Antarctica#Creating_an_Antarctica_map and also https://wiki.openstreetmap.org/wiki/Antarctica/Creating_a_map

I suggest also https://blog.jochentopf.com/2013-02-04-antarctica-in-openstreetmap.html and https://help.openstreetmap.org/questions/29521/mapping-rendering-antarctica

If you have ideas or suggestions on how to improve this it would probably best to do so in the wiki, mailing list, forum or some other place that is better suited for that.