I fixed 2 problems

1. Created XML file causes encoding error for some data.

in Render() I changed line

cContents = STRCONV(cContentsToBeRendered, 6)

to

cContents = STRCONV(strt(strt(strt(cContentsToBeRendered, ;
   '&','&amp;'),'>','&gt;' ),'<','&lt;'),9)

2. Since color columns in frx file can have value -1,
REPLACE in AfterReport() causes error. I changed replace to

REPLACE ALL cExcelInterior WITH 'Solid,';
    	+ RIGHT(TRANSFORM(RGB(FillRed,FillGreen,FillBlue),'@0'),6) + ',' ;
		+ RIGHT(TRANSFORM(RGB(PenRed,PenGreen,PenBlue),'@0'),6) ;
	FOR ( FillRed # 255 OR FillGreen # 255 OR FillBlue # 255 ;
				OR PenRed # 0 OR PenGreen # 0 OR PenBlue # 0 ) ;
    AND FillRed # -1 AND FillGreen # -1 AND FillBlue #-1 AND ;
	     PenRed # -1 AND PenGreen # -1 AND PenBlue # -1

Unresolved issue:

Fontcharset support. RESOID field in frx file. In VFP9 this field
contains Fontcharset value for rows where OBJTYPE is 5 and 8 (text
fields and labels)

STRCONV() must be called with nRegionalIdentifier parameter in Render()

CharsetTolocale() method in frxcursor class can be used
to convert Fontcharset value to nRegionalIdentifier.

How to call CharsetTolocale() in Render() ?