Hi Cris72,
I have the same issue

.
The "required" property is recognized by Adobe Reader (v11), the textfields are lined out red, but I can send the form even when nothing is typed into the field.
If I add a textfield to the form through Acrobat Pro and give it exactly the same properties as the Scribus textfields, Adobe Reader does what it should and gives me the appropriate warning.
It is as if the Reader notices that a field was created outside Acrobat and ignores the validation.
I am not shure, but I think in former versions of Adobe Reader I did not encounter this problem. Since this seems to be rather a problem from Adobe, I doubt that there will be a solution in Scribus.
To solve this issue, there may be no other way than to add explicit validation code in JavaScript to the document.
I hope that I am wrong, so please anyone correct me and present a solution to this issue

!
Cheers