Darned clever. Too bad that: 
balanced_delimiters('(\a)', '(', ')', "\\")

[download]
returns the wrong thing. Perhaps you meant this? 
sub balanced_delimiters {
    local $_ = shift;
    my %sub;
    @sub{@_} = ("(",")");
    my $LRS=join'|',map quotemeta,@_;
    $LRS .= "($LRS)";
    {local $^W=0;s/($LRS|.)/$sub{$1}/gs; eval{m/$_/} }
    return !$@;
}

[download]
A behaviour note, the escape sequence properly escapes the escape sequence.

In reply to Re (tilly) 2 (fails): Determining if you have balanced delimiters by tilly
in thread Determining if you have balanced delimiters by Ovid

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