$ perl -E '
    my @exceptions = (
        "ERROR (EABC): Error message 1",
        "WARNING (WPQRST): Error message 2",
        "ERROR (EWXYZ): Error message 3",
    );
    my $re = qr{^(?:ERR|WAR)[^:]+: \K.+$};

    for my $e (@exceptions) {
        my $timestamp = localtime;
        $e =~ s/$re/[$timestamp] $&/;
        say $e;
        sleep 2;
    }
'
ERROR (EABC): [Fri Oct  6 02:56:17 2023] Error message 1
WARNING (WPQRST): [Fri Oct  6 02:56:19 2023] Error message 2
ERROR (EWXYZ): [Fri Oct  6 02:56:21 2023] Error message 3