1)http://track-chinapost.com/result_china.php?order_no=UI135047831CN shows the parcel was shipped on Mar 3.

this kind of parcel starting with U is china post ordinary parcel. China Post will not scan and update its status after it left first post office. so you can not see new status and know where it is now.

This is a slow and cheap service for low value item. china post ordinary parcel might take 4 to 12 weeks to reach your country.
2)
http://track-chinapost.com/result_china.php?order_no=RG974164173CN shows the number was sent to airline on Mar 30.

China Post will lost control of the parcel after sent to airline. so there will be no update anymore after sent to airline date.

Sent to airline does not mean you will get the parcel very soon. It will keep waiting 5 to 10 days in airline warehouse waiting flight space and another 1 to 4 weeks import customs processing in destination country(speed depending on country). The status will stuck at "sent to airline" during this 2 to 8 weeks period.

Once it passes import customs clearance, Italy Post will scan and update its new location for China Post database and you will see new status.

If your buyer protection is expiring, open dispute for refund. Otherwise keep waiting.