Did you already tried to print the desired values from %inputs to see if they are really set?

Did you check, what's defined in %inputs (maybe a Typo bothers you here)?

I would check if $inputs{"Requester Email"} exists and is defined when assigning it as new Value..e.g.

$derfref = {
  new_key => exists $inputs{old key} and defined $inputs{old key} 
      ? $inputs{old key} : "--no old key--"
};
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