I am attempting to use a character from the ESRI Environmental & Icons font collection (A bird in particular). I went into my character map tool and found the one I want (symbol right parenthesis). With the formatting tags, the input looks like this:
<BOL>Country Y</BOL><FNT name="ESRI Environmental & Icons"> )</FNT> Disease X Total Avian Cases: 12,345 <FNT size="8">Since: 01 JAN 2016 </FNT>
I had no problems using a different character set (ESRI US Forestry 1, for example). I suspect it has something to do with the "&" in the font title. I also tried using "ESRI Environmental & Icons Regular," which is how it's listed in the font folder on my system.