Due to having to pretend not to remember previous loops Sentius has to perform the same actions and dialogue every day, which must be incredibly tedious. It's no wonder he expresses perverse amusement in Al Worth's increasing desperation seeing as his actions are the one source of variation in his life.
This is true but it is also not a great burden. Most days the traveler will meet with him cursorily to exchange notes and possibly identify the sinner, but otherwise going on their way, allowing Sentius to live whatever a monster considers his Best Life for most of the day until someone inevitably cocks it up and he has to invoke the ritual again. He also only has to keep up the facade when Al Worth or the player is around, and even then not after the reveal precisely because he can singlehandedly screw with everyone, as he handily demonstrates if you try to tell his remaining daughter about his true nature. So Sentius has quite literally all the time in the world, and keeping up a charade for at most a few hours per "day" is a small price to pay for immortality.
Unless Pluto confiscated it then the Golden Bow of Diana is still somewhere in the Forgotten City, just waiting for one enterprising archaeologist to discover and use it to irrefutably prove the existence of advanced precursors and/or wreck the economy with unlimited gold.
The Golden Bow of Diana is said to be advanced technology of the gods. The fact that it can entomb living beings in gold while keeping them alive and conscious is horrifying and given Diana's status as a hunter it's possible these were used to turn people into living trophies. Alternatively it may have been intended to simply preserve creatures and give them life later (like with Pluto's Furies) but the technology is still ripe for abuse as Pluto shows.
While walking round the city the player will intermittently hear a scraping noise like a blade being sharped. Eventually they'll realise it's the sound of the statues turning their heads to face the player when they aren't looking.
Sentius's time loop immortality plan, as well as ruining the life of Al Worth and potentially the player, would also have guaranteed his death and that of every member of the city. Sentius believed he would simply be sent a new divine agent when the player died and he could keep doing this forever, but Charon reveals that Al Worth and the players' two obols were the last in existence, meaning no-one else would ever be brought to the city.
It's mentioned that some of the original silver obols were melted down into silver trinkets. Imagine getting dragged into an underworld run by an abusive god just because you happened to be wearing a random piece of jewelry when you died.
The fact that the gold statues come back to life in the Golden Ending means if the player shot any skinned statues with normal arrows instead of turning them to gold they are likely dead for good.
Pluto's Furies who willingly exterminated the city's residents whenever the Golden Rule was broken are presumably among those returned to life.
When asking Sentius for the key to the Cistern, he immediately refuses on the grounds that he can't just let anyone take it because of how easy it is to cripple a town by poisoning its water supply. Aside from the fact that that's where he's imprisoned Sentilla, why is he so familiar with this particular tactic? Given his background in the Roman military, it is entirely possible that he has used it himself against other perceived "enemies" in the past.
