Your sample code does not correspond to your sample data.
The regex of your sample code will not match the sample data because the literal characters "Value of field name" are not present in your data.
Try something like this:
$
$
$ cat f14
Original Order Tuple
Duplicatel Execution Tuple
$
$
$ perl -lne 'print "The word right before \"Tuple\" is \"$1\"" if /.*\b(\w+) Tuple$/' f14
The word right before "Tuple" is "Order"
The word right before "Tuple" is "Execution"
$
$