I tried in vain to list the MacOSX fonts in mtxrun.

In my .bashrc set: 
OSFONTDIR=$HOME/Library/Fonts:/Library/Fonts:/System/Library/Fonts
export OSFONTDIR

Then issuing the following commands:
source ~/.bashrc
echo $OSFONTDIR
/Users/hansm/Library/Fonts:/Library/Fonts:/System/Library/Fonts
mtxrun --script fonts --list pattern="Comic*" --all
resolvers       | trees | analyzing '/Users/hansm/Documents/TeX/texmf'
identifier   familyname   fontname   filename   subfont   instances

Allthough there are definitely Comic fonts (such as Comic Sans MS.ttf) in directory /Library/Fonts these are not listed by mtxrun.

What is happening, or better, not happening here?

Hans van der Meer