Steps to Reproduce

Very specific use case, but my question is about the fundamental mechanics in mono about fonts

1. install ubuntu 18.04.2
2. install mono 5.20.1.19 (tarball Thu Apr 11 09:02:17 UTC 2019)
3. unzip latest Maperitive package ( a .net application)
4. mono --desktop Maperitive.exe
5. load Maperitive rules and osm file

Current Behavior

Arabic and Tifinagh letters are shown as boxes, WHILE on Linux level the osm input file is properly displayed, incl. Arabic and Tifinagh names

Expected Behavior

Arabic and Tifinagh letters should also be shown in their proper rendition

So the question arises: how does mono leverage - or fail to leverage the Linux system fonts ?