You aren't creating your %lang_dev hash correctly. If you want to break it apart by commas, you need to read each line, split on the comma, and store it:

while (<LANGUAGES>) {
   chomp;
   my ($key, $value) = split /,\s*/;
   $lang_dev{$key} = $value;
}
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Your method for pulling the data from a hash reference should be fine, but you might also consider writing it this way (which in my opinion is a bit more clear)

Editor's note: This post originally included tekniko's question, properly formated. Since I added the formatting tags to the question, I removed the duplication from this post.

Originally posted as a Categorized Answer.