Seems to me that, before you process with a standard module, you need to eliminate instances of double-doublequotes.

E.g.

  $i = '“R50””R20”,””Desc 4-10””,”R400,20”,Test,”Test5””””';
  $i =~ s/\"{2}/*my_special_double_quote_marker*/g;
    ... normal double quote processing here ...
  foreach ( @cell ) {
      s/*my_special_double_quote_marker*/\"/g;
  }
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