Change language domain isn't good idea :-(
You forgot to rename your language definition files.
You define $skin_change_note in __construct() with __() function, but in this time language domain isn't set yet and text isn't translated.
I try assign a plain text to $skin_change_note and __() use until during filling $ret. (load_plugin_textdomain placed in __construct() doesn't cooperate with native dashboard plugin)
I thing i cannot add skin by copying via ftp. Or do?