Well because I really don't want to turn strict off... strict is lexically scoped, you don't have to turn it off for the whole program

no strict;
if (defined $$newvarname) {
    $$var = $$newvarname;
}
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but that will only work of the vars are our vars

I'm just not seeing how to implement the alternatives in my specific case.

You could improve upon your description ( post a more complete question), I don't see why a hash couldn't work

my %hash = ( qw/ foo 1 bar 2 baz 3 / );

$array[$user_section] =~ s{
    ^ username => (.*) $
}{
    Dance( \%hash, $1 );
}xemg;

sub Dance {
   my( $vars, $one ) = @_;
   my $name = $vars->{$one};
   return "username => $name" if defined $name;
   die "no name for $one ";
}
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