My Jasper Report template is an A4 portrait with 0.5 in margins all sides. When DOCX is generated from it via library (with only special setting being setting frames as nested tables), the output has 0.5 margins in all sides except for the bottom which has 0.25. I increased the margin of the bottom in the template to 0.75 and the output had 0.5 bottom margin. I also tried via the eclipse Jasper Studio plugin exporter and same behaviour as with library.
Using Version 6.4.3