At first, i'm sorry. I don't speak italian, but i can read a few words.
The answer of the question is in the db.
In the table "jos_content" u can see the properties that you can get from the object $item of the mod_newsflash. (see the /modules/mod_newsflash/tpl/_item.php file).
There, we can find the the informations of all articles, including what you want: "publish_up", and "created".
So, what you have to do is get the information like this: $item->publish_up or $item->created and put it into the JText pattern.
Like:
<?php echo JHTML::_('date', $item->publish_up, JText::_('DATE_FORMAT_LC2')); ?>
or
<?php echo JHTML::_('date', $item->created, JText::_('DATE_FORMAT_LC2')); ?>
I wish it could help. Cheers from Brazil.