By the way, the Barred O symbol (Ө) on this keyboard is not correct. This keyboard specifies an input of CYRILLIC LETTER FITA (Ѳ) for key code 39, corresponding to Unicode Ѳ (upper case) or ѳ (lower case). The actual Mongolian alphabet specifies CYRILLIC LETTER BARRED O, using different Unicode references.
You can fix this by editing the file and changing the first entry for key code 39 to look like this:
<key code="39" output="ө"/>
and the second entry to look like this:
<key code="39" output="Ө"/>
Word of warning, doing so in a typical text editor may break the file. I used vim from the command line and it worked.