@hash2{ 0 .. (keys %hash)-1 } = map { $hash{$_} } sort {$a <=> $b} key
+s %hash;
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You had it right before; why did you think you need the map there?

@hash2{ 0 .. (keys %hash)-1 } = @hash{ sort { $a <=> $b } keys %hash }
+;
[download]

I'm too lazy to verify, but I think you don't need to assign to a separate hash if you do it this way, either. The list should be assigned atomically once it is built completely.