I tried converting the below MathML code,
AB=2
The Latex output was as below (with an additional ')' added inside the overline),
\overline{)AB}=2
This is due to an additional parenthesis defined inside the glayout.xsl as below (line 166),
xsl:text\overline{)</xsl:text>
Solution is to remove the paranthesis as below,
xsl:text\overline{</xsl:text>