For this method, I have the following suggestion:
If the legends or categories arrays are a different size than the source chart, adjust the legends/categories to match the replacement data. Currently, if the replacement data legends/categories are a different size, the chart is placed in somewhat of a corrupted state.
If the preferred option cannot be implemented, an exception should be thrown when the replacement data legends/categories are a different size than the source chart. I realize the developer can check this but within the boundary of DocxUtilities, the class should not allow the developer to pass data that places the chart in a corrupted state without throwing an exception or providing some feedback to the developer.