Couple things to look at:

1. If you are new to installing modules with CPAN, be patient.   It is an acquired taste.
2. Make sure that you know where the modules (like Text::Unaccent actually have been placed.   Validate that they actually are there.   Make sure that you did the entire module-install process and that all of it worked.
3. Once you are sure that the modules were correctly installed into some directory, be sure that it’s in @INC.
4. “Well, mistakes sometimes do happen.”   A module is supposed to name all of its prerequisites and co-requisites correctly, but, the possibility remains that maybe something got overlooked.   Every now and then, you will encounter a situation where you find that something is missing and have to install it.   (Once you have installed the prereq, re-install the dependent module again.)   I do not know whether this sort of thing did happen here, but it can.