Another approach is to leave the string of concatenated key fields as it is and use it alone as the hash key:

Win8 Strawberry 5.8.9.5 (32)  Wed 08/31/2022 21:20:10
C:\@Work\Perl\monks
>perl

use strict;
use warnings;

use Data::Dump qw(dd);

my %config;

sub set_config_value {

    my ($hr_config,  # hash ref.: configuration hash to fill
        $key_seq,    # string: multi-key sequence, hyphen-separated
        $value,      # string: value of multi-key sequence
        ) = @_;
  # dd '---', '$key_seq', $key_seq, '$value', $value;  # for debug

    push @{ $hr_config->{$key_seq} }, $value;

    }

sub get_config_value {

    my ($hr_config,  # hash ref.: configuration hash to fill
        @key_seq,    # list: multi-key sequence to get value of
        ) = @_;
  # dd '===', '$key_seq', \@key_seq;  # for debug

    my $multi_key = join '-', @key_seq;
    die "key sequence (@key_seq) not in config hash"
        if not exists $hr_config->{$multi_key};

    return $hr_config->{$multi_key};

    }

for my $ar_add (
    [ 'address-virtual-email',     'rpaskudniak', ],
    [ 'address-virtual-email',     'rasputin',    ],
    [ 'address-virtual-email-foo', 'fred',        ],
    [ '',                          'emptystring', ],
    [ 'bag-end',                   'frodo',       ],
    ) {
    my ($key_sequence, $val) = @$ar_add;
    set_config_value(\%config, $key_sequence, $val);
    }

dd \%config;
dd get_config_value(\%config, qw(address virtual email foo));
dd get_config_value(\%config, '');
dd get_config_value(\%config);

^Z
{
  "" => ["emptystring"],
  "address-virtual-email" => ["rpaskudniak", "rasputin"],
  "address-virtual-email-foo" => ["fred"],
  "bag-end" => ["frodo"],
}
["fred"]
["emptystring"]
["emptystring"]
[download]

An elaboration of this would be to make the set_config_value() function accept a variety of separator sequences by adding a step like (untested):
    $key_seq =~ s{ \s* (?: => | [-,=]) \s* }{$;}xmsg;
(get_config_value() then has to be changed to join with $; - see perlvar.)