As I have nearly all available ships from here running in my modded install, i can only offer a possible solution why you did not get these Italian DDs to work;
there is one big "master"classfile, that relates to most if not all of Gios ships in the game and if you have any of these running and want to get Gio´s supposedly older Italian DDs running as well, you need the biggest classfiles labelled 4799D4F0B7F09D3E ... I can provide it of course, but if you use it, you might need the other ships included in there as well;
the original download for these two DDs comes with 5 classfiles, one of them the mentioned one, but in a very small and basic version;
two classfiles related to the German Z7 and Z29 destroyers, you do not need those I guess, at least I do not have them in my Navigatori/Poeti folder;
so if you want to try again and get Poeti and Navigatori to run, make sure to check for the lastest available version of the 4799 classfile....
mine is 14,4KB in size and has a date stamp from 6th September 2012...