You can translate attributes of package.xml like:
<Description>Miam-Player is the main program. It is required and cannot be
unselected.</Description>
<Description xml:lang="fr_fr">Miam-Player est le programme principal. Il
est requis et ne peut être désélectionné.</Description>
but this does not work with config.xml
How do you translate attributes of config.xml such as 'Name', 'Title' etc. ?