Hi there!
Fresh install, uploaded the it.phar file to include/i18n, set the primary system language to Italian, went to email/templates, created a net template from stock choosing italian as a language, but when I try to edit the template the email text it still shows content in English. Is this working as designed or am I missing something?
Mail templates are not translated. You have to do it yourself.
I beg to differ. Apparently the translation is there
but for some reason in $PREFIX_email_template entries are not created and populated for the corresponding tpl_id.
Yes, I know that these texts are contained in the PHAR archive, however the content of the templates is stored in the database in the table ost_email_template.
Leaving here, if anyone should stumble on the same problem.
1) downoad the phar file from osticket
2) create a subdir in the include/i18n directory with the ISO code of interest (for me it was it_IT)
3) uncompress the phar file
3) copy the uncompressed phar content in the subdir created as per 2
4) chown as needed the subdir at hand
After that, if your language pack includes the email templates you can use them as you see fit.
HTH someone 
