Bug 202121 setDateFormat does not working
If you want to set date format of the table column style you have to use setDateTimeFormatCategory and setDateTimeFormat instead of setDateFormatCategory and setDateFormat. If you will try to use setDateFormatCategory in the first case in xml-source you will see that your style contains dateFormat property. This property is not working at all, in the second case in xml-source you will see that your style contains dateTimeFormat property. I think it will be better if the result of setDateTimeFormatCategory and setDateFormatCategory will be the same.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/presentation/LocalizedContentVisitor.java
URL url = reportDesign.findResource( image, IResourceLocator.IMAGE );
			if ( url != null )
			{
				style.setBackgroundImage( url.toExternalForm( ) );
			}
		}
	}
	
	public IContent localize(IContent content)
	{
		IStyle style = content.getInlineStyle( );
		processBackgroundImage( style );
		Object value = content.accept( this, content );
		return (IContent) value;
	}
	
	protected IContent localizeAllChildren( IContent content )
	{
		ArrayList children = (ArrayList) content.getChildren( );
		if ( children != null )
		{			
			for ( int i = 0; i < children.size( ); i++ )
			{
				IContent child = (IContent) children.get( i );
				IContent localChild = localize( child );
				if ( localChild != child )
				{
					
					children.set( i, localChild );