The UAI for uni students is typically a hidden process. As such no data is available to us to create a UAI estimator based on uni marks. And normally, other factors are taken into consideration besides uni marks, such as the year 12 UAI.
Also, a NRSL (non-recent school leavers) cut-off is used for students who have already completed a year of uni. And those cut-offs are not publically revealed either.