I too tested the Halo MCC Halo 3 Trainer dated 09-26-20 and got the exact same error. what a shame I hope it can be fixed.
17:53:35: Successfully attached to MCC-Win64-Shipping
17:53:36: Collect Player, Script error in line 9: Cannot find aob for 'Collect_Player'
We know, takes time to re-write every trainer in the Halo series, just need a lil patience...
Yes, see my post above.