For the issue (Legend Reversed):
The Legend Reversed issue is not resolved. I have posted the issue on a different thread.
I have tested and it is fixed already with v18.104.22.168 (please try this version (attached)).
Following is my test code. I have extracted the excel chart from your ppt file and take the image of the chart sheet. You can confirm that the issue is resolved.
Here is my sample code:
Workbook book = new Workbook();
ImageOrPrintOptions imp = new ImageOrPrintOptions();
imp.ImageFormat = System.Drawing.Imaging.ImageFormat.Emf;
Please try the attached version to check whether it fixes the legend's reverse items issue.