title: setFormulaR1C1() doesn't translate to A1 notation in all cases...?
body: <p>I'm trying to write a function that sets a formula in a cell using relative R1C1 notation because I don't know what row number the cell will have. I've used cell.setFormulaR1C1(string) successfully twice, but in a third case I'm not sure what's not working.</p>
  
  <p>When I pass this string to setFormulaR1C1() applied to cell H34</p>
  
  <pre><code>"=R[0]C[-4]*VALUE(IFERROR(REGEXEXTRACT(INDEX(CSE!I:I;MATCH(R[0]C[-6];CSE!A:A;0);1);\"[0-9]+\");\"0\"))" ;
  </code></pre>
  
  <p>should spit out </p>
  
  <pre><code>=D34*VALUE(IFERROR(REGEXEXTRACT(INDEX(CSE!I:I,MATCH(A34,CSE!A:A,0),1),"[0-9]+"),"0"))
  </code></pre>
  
  <p>...right? But instead it is not translating the string into A1 notation and I receive a parse error. The backslashes </p>
  
  <p>Elsewhere I have had success using a very similar formula...</p>
  
  <pre><code>paymentDueFormulaCell.setFormulaR1C1("=R[0]C[-3]-R[0]C[-2]-R[0]C[-1]");
  </code></pre>
  
  <p>which, when set into cell J34 gets correctly rendered as as</p>
  
  <pre><code>=G34-H34-I34
  </code></pre>
  
  <p>Can anyone intuit the differences I might be missing?</p>