Thanks for using Aspose.Cells.
If you open the template file and generated file in Excel 97-2003, the shadow effect is same. The chart must be created by MS Excel 2007 or above version. We do not support advance shadow effect setting in xls file since ME Excel 2007 and the feature could not be supported soon. Please simply save it as xlsx file now.
Please download and try the following fix and let us know your feedback.
The issues you have found earlier (filed as CELLSJAVA-41860) have been fixed in Aspose.Cells for Java 18.6. Please also see the document for your reference: https://docs.aspose.com/display/cellsjava/Installation