If we get the same number of points per action as in the Pigsy event, this Castle is very hard. Consider the case where you always find the key in the last chest. Then the first level needs at least 4955/(6*150) cycles, thus 6 cycles, 445 points remaining. The second one needs at least

(4955+3476-6*6*150)/(6*200) cycles,

thus 3 cycles, 569 points remaining. Similarly one needs further 5,6,6,15 cycles for levels 3,4,5,6. These are 41 cycles, thus 10 days and 6 hours. I think we start with a few extra points, and maybe there are other sources like the Whale Mart, but it is going to be tough.

4955 is just a very high number of points for the first level. Maybe they change something about the rules again to make it doable, or they make the keys appear in earlier chests.

OTOH when you get at most 400 points per action in every cycle, and altogether you need 73862 points for both Divines, you cannot be faster than 73862/(6*400) cycles, thus 31 cycles or 7.7 days (not including points from other sources).