From the previous reports, if the thing was launched in China, then that must be what happened. From January to March, whenever there is a La Niña system dominating in the Pacific, then the polar jet stream is almost identical to the balloon track. The likelihood of the balloon passing along this track would be well known and. therefore, quite predictable.
Map from NOAA: https://www.pmel.noaa.gov/elnino/lanina-faq