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Now comes the problem: We know the answer is $32$ 50% of the time and we know the answer is somewhere in $[1-5]$ the other 50%. We know the devil chose each with equal probability because of how the peasants were guessing. That means the final answer is $47$.

There are problems in the question's wording:

1. We're only assuming that each peasant can count to 5 but, based on the wording of what the peasant said, it's more likely that most can't.
2. The devil, being not so very nice, could have had a different scheme for the robots and peasants. There's no reason why, when it's a peasant, he picks $[1-5]$ 50% of the time and $[6-32]$ 50% of the time while for a robot he picks $[1-31]$ 50% and $[32]$ 50%. The final answer can be anything between $33$ and $528$.
3. If the peasants guess randomly in the set $[1-5]$, then it's possible for the devil to pick, say, $3$ 50% and $32$ 50%. Depending on when they peasants randomly guessed $3$, that gives the 20% / guess result. The final answer can be anything between $33$ and $47$.
4. The robots could have picked 17 as their midpoint which can shift which number(s) they'll never guess. In that case, the answer can be anything be as low as $19$.
5. The peasants can only count to $5$ but that doesn't mean they don't know other numbers exist. It's possible for the devil to pick a number higher than $5$, the peasant randomly guesses $5$ first, the devil says "Higher", and the peasant says, "Uhhh... 14?". The wording only implies that the peasant doesn't know numbers higher than $5$.

We can safely conclude that the robots did not pick $17$ as the first midpoint. They are deterministic and do not like randomness so we can assume they all followed the same scheme. Similarly, it follows that, had they picked the higher midpoint, then they would have always picked the higher midpoint. That means the lower half would split at $17$, $9$, $5$, $3$, $2$. In that case, they would have never chosen $1$ as an answer instead of never choosing $32$. However, they could have solved for any number $[2-32]$. If 50% of the robots go to hell, that means that the devil picked $1$ 50% of the time. This contradicts with what we know based on the peasants' pattern. Therefore, we reject $17$ as the first midpoint.

Now comes the problem: We know the answer is $32$ 50% of the time and we know the answer is somewhere in $[1-5]$ the other 50%. We know the devil chose each with equal probability because of how the peasants were guessing. That means the final answer is $47$.

There are problems in the question's wording: (All have been clarified by OP)

1. We're only assuming that each peasant can count to 5 but, based on the wording of what the peasant said, it's more likely that most can't.
2. The devil, being not so very nice, could have had a different scheme for the robots and peasants. There's no reason why, when it's a peasant, he picks $[1-5]$ 50% of the time and $[6-32]$ 50% of the time while for a robot he picks $[1-31]$ 50% and $[32]$ 50%. The final answer can be anything between $33$ and $528$.
3. If the peasants guess randomly in the set $[1-5]$, then it's possible for the devil to pick, say, $3$ 50% and $32$ 50%. Depending on when they peasants randomly guessed $3$, that gives the 20% / guess result. The final answer can be anything between $33$ and $47$.
4. The robots could have picked 17 as their midpoint which can shift which number(s) they'll never guess. In that case, the answer can be anything be as low as $19$.
5. The peasants can only count to $5$ but that doesn't mean they don't know other numbers exist. It's possible for the devil to pick a number higher than $5$, the peasant randomly guesses $5$ first, the devil says "Higher", and the peasant says, "Uhhh... 14?". The wording only implies that the peasant doesn't know numbers higher than $5$.

If 50% of the peasants get to heaven and peasants can only count to 5, that means that the numbers is in the set $[1-5]$ 50% of the time and in the set $[6-32]$ 50% of the time.

Peasants will guess all the numbers in the set $[1-5]$ in some order.

Now comes the problem: We know the answer is $32$ 50% of the time and we know the answer is somewhere in $[1-5]$ the other 50%. However, the devil could have chosen any combination of $1, 2, 3, 4, 5$ so long as the total count was 500. That means the final answer is anywhere from $33$ to $47$.

Caveat: If we assume that all the peasants actually counted $1-5$ in order, then that means that the devil picked all those numbers with equal probability. This possibility is implied in the question but not explicitly stated.

In that case, the final answer can be determined to be $47$.

If 50% of the peasants get to heaven and peasants all know the numbers $1-5$, that means that the numbers is in the set $[1-5]$ 50% of the time and in the set $[6-32]$ 50% of the time.

Peasants will guess all the numbers in the set $[1-5]$ in some order. We know they don't perform a binary search like the robots because, if they had, they would always get it right by the 3rd guess (or not at all). We know they got it right with equal probability for each guess to they either pick the numbers randomly or simply count from $1$ to $5$ with the devil saying "Higher" each time.

Now comes the problem: We know the answer is $32$ 50% of the time and we know the answer is somewhere in $[1-5]$ the other 50%. We know the devil chose each with equal probability because of how the peasants were guessing. That means the final answer is $47$.

Caveat:

There are problems in the question's wording:

1. We're only assuming that each peasant can count to 5 but, based on the wording of what the peasant said, it's more likely that most can't.
2. The devil, being not so very nice, could have had a different scheme for the robots and peasants. There's no reason why, when it's a peasant, he picks $[1-5]$ 50% of the time and $[6-32]$ 50% of the time while for a robot he picks $[1-31]$ 50% and $[32]$ 50%. The final answer can be anything between $33$ and $528$.
3. If the peasants guess randomly in the set $[1-5]$, then it's possible for the devil to pick, say, $3$ 50% and $32$ 50%. Depending on when they peasants randomly guessed $3$, that gives the 20% / guess result. The final answer can be anything between $33$ and $47$.
4. The robots could have picked 17 as their midpoint which can shift which number(s) they'll never guess. In that case, the answer can be anything be as low as $19$.
5. The peasants can only count to $5$ but that doesn't mean they don't know other numbers exist. It's possible for the devil to pick a number higher than $5$, the peasant randomly guesses $5$ first, the devil says "Higher", and the peasant says, "Uhhh... 14?". The wording only implies that the peasant doesn't know numbers higher than $5$.

It seems to me that the problem is indeterministic which probably means I'm missing something.

It seems to me that the problem is indeterministic which probably means I'm missing something. At the very least, it's too loosely worded.