The style editor is pretty awesome (the one found in the Classic map viewer).
This suggestion is related to fonts. I am not a windows user, so "Arial Unicode MS" is not present for me, and on my openlayers map, all the labels are in a serif font (gross).
I don't particularly want to load a special font on my web page. I want to specify "sans-serif" in my style, which is a fallback font name that lets each browser choose an appropriate font face. I can set this in my style by downloading it, manually modifying the JSON, and uploading. However, after I do this, no labels appear in the map viewer.
I render tiles in OpenLayers using ol-mapbox-style, so they appear properly, but it would be nice if the style editor and map viewer could handle the "sans-serif" text-font value properly. "sans-serif" is a standard thing in web development.