We were able to observe the issue but we need to look into it more. We have logged the issue in our database for investigation and for a fix. Once, we will have some news for you, we will update you in this topic.
This issue has been logged as
CELLSNET-46389 - Converted EMF image looks different from the original Excel chart
We are afraid, the position issues cannot be fixed for now. We can read the position of lines that are sub-shapes of chart is recorded in Excel file. But the chart elements position is not documented in the Excel file. So, we need to calculate them. Now, calculating the position is too complex to sort out. We cannot do it same as Excel for now.