Hi! This can stay inside TyranoBuilder: after either Collect or Forgive, set one game variable to a fresh random integer from 1 to 3, then use three conditional Jump components to route that saved value to the corresponding ending. Generate the number once per choice, rather than separately inside each jump condition. The same ending can legitimately appear twice in a row.
The official variables tutorial covers random values and conditional jumps: https://tyranobuilder.com/tutorials/more/using-flags-and-variables-tyranobuilder
If you would like help mapping this to your existing scene, I can review a screenshot of the relevant components and offer a small $15 setup/diagnostic task, targeting 24 hours after we confirm the scope. No story details needed. If email works for you, please contact yeqingdeng23@gmail.com or reply here with your TyranoBuilder version and whether Collect/Forgive share the same three endings. I would confirm compatibility before taking payment.