Right now the main OpenStreetMap.org stylesheet uses Unifont as a fallback for characters not in the DejaVu font. As Unifont is designed to support all characters and not to look good, this can lead to ugly and difficult to read text in parts.
It looks like the tone characters are being hit by a bug in Mapnik (https://github.com/mapnik/mapnik/issues/2161), leading to them being placed too high. I doubt this is going to be fixed immediately, these problems have taken time in the past.
With this bug, do you think it’s still an improvement?
Also, although it looks bigger, the actual font size is the same. The difference has to do with relative heights of letters, and the old font being so ugly.
tone marks look fine on Thaimap. Can some native speaker please confirm? Also Thaimap renders a lot more street names in Thai which are simply mission on osm.org. I guess 20% of the names are missing there.
I looked at Loma, but Arundina has better DejaVu compatibility. The data on my server is a couple months old, so it probably has less names for that reason. I’m loading up a new extract to test Khmer, and I’ll refresh the tiles then.
My work is also based on the latest openstreetmap-carto revision, and I 'm not sure what thaimap uses.
The changes have been merged and are now in use on openstreetmap.org. There are the tone character bugs, but we need a new Mapnik release to fix those. There are also the same bugs in nearby countries with similar complicated language features.