Font problem

[root]

To anyone who might listen:

While trying to give my first steps with liylpond, I got the following
error messages in the terminal:
- can't find file 'feta20'
- can't find file 'feta-nummer10'

The files were compiled anyway, but the characters were strange, even
that all the notes were in place.
I've looked for those files, and they were in several folders, including
in the make paths, so I'm not sure what to do to prevent this.

Thank you for your help,

João M Pais