in reply to add letters to the begin of the sentence

Move the print after the unless block. You should only substitute for non-headers, but the unchanged lines should be printed as well.
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In Section Seekers of Perl Wisdom