Actually, the BWGRKL font is designed for use in the BibleWorks program, and may not always produce the expected results in other programs. A check of this key bore this out in MS Word. In BibleWorks, the key produces a combination soft-breathing mark with a grave accent mark. This is placed over the immediately preceding letter that was typed. In other programs, such as Word and InDesign, they are not accessing the code table in the same way, so the character that results will be the double plus sign that you encountered. There may be others that behave like this.