Table with specified width in inches is not correctly exported when the size is set in inches (this is  done in the imported HTML) 

Workaround: set the table size in the code and remove the style.

foreach (Table table in document2.EnumerateChildrenOfType<Table>())
{
    table.LayoutType = TableLayoutType.FixedWidth;
    table.PreferredWidth = new TableWidthUnit(TableWidthUnitType.Fixed, 950);
}