Thanks for your posting and using Aspose.Cells.
Please create your desired shape in MS-Excel manually and save it on disk and then load it with Aspose.Cells API and check its all the properties in Debug
or Quick Watch
. It will help you create the replica of the shape from scratch and then you can modify it as per your needs. Please see the attached screenshot
, it is showing the properties of ElbowConnector shape loaded from the attached excel file.