http://track-chinapost.com/result_china.php?order_no=UG979439918CN shows the parcel was shipped on Oct 6.
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.

http://track-chinapost.com/result_china.php?order_no=RY346507358CN shows the number was sent to airline on Oct 23.
China Post will lost control of the parcel after sent to airline. so there will be no update anymore after sent to airline date.
After sent to airline, parcel will travel another 6 to 12 weeks to reach Costa Rica. You might need wait some more time.