Hi,
I will explain it here :
1. In mod_install.xml you can use double curly braces instead of the original text. E.g. I want to translate the plugin name "Smart Maintenance Mode" so I will replace it as follows :
<head>{{maintenance_mode}}</head>
2. Now in mods.php in __wp_mod_settings function please globalize $softlang e.g.
global $softlang;
3. Now add your translated strings in this function after globalizing the array e.g. :
$softlang['english']['maintenance_mode'] = 'Smart Maintenance Mode';
$softlang['french']['maintenance_mode'] = 'Mode d\'entretien intelligent ';
Make sure the keys in $softlang matches the values you want to replace within double curly braces {{}} in the mod_install.xml
Let me know if you face any issues.