Possible to insert new line / break in messageTop?

Hello,
I have header and footer legend notes that I'd like to append to my exported XLS file. I was thinking that I could somehow include "\n" and then they'd go to the next line, even if all the text was in one cell. Is that possible?

I have tried a few things I've seen people try:

                        exportOptions: {
                            stripNewlines: false
                        },  

And:

            var data = output_table.buttons.exportData( {
                modifier: {
                    stripNewlines: false,
                    stripHTML: false
                }
            } );    

But I'm not having any luck. Is this possible? I'd love to have a list of items in the footer (or header) if I can.