To answer your original question:

This line of code extracts the search string from the config file:

    ($string[$i], $action[$i], $actionargs[$i],
    $numrows[$i]) = split /\t+/, $_;
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And this line decides if the logfile has a match:

    if ($_ =~ /$string[$str_index]/i) {
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As far as I can tell, if you were to put a regular expression in for your string in the config file, it would directly interpret it as such. This is a direct conflict with your statement that it doesn't take regular expressions.

Have you tried

orchestral.*execution    mail    1
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at all? Because unless I'm missing something (and I sort of skimmed the code so it's of course possible), it sure looks to me like it would work.