I have observed the requirements shared by you and like to share that Aspose.Slides allows setting X and Y position for ITable inside presentation. You can set the position based on your requirements on your end. As a suggestion in order to meet your requirement you may try using the following approach for setting X position of table inside slide.
Presentation pres=new Presentation(“Test.pptx”);
table.X=(pres.SlideSize.Size.Width - table.Width)/2;
I hope the shared sample code will be helpful. Please share, if I may help you further in this regard.