I hope all is well,
Sorry to hear that you are having issues with the formatting of text files from exporting. Having tried to replicate this I couldn't quite see the results that you seem to be getting.
With this, would it be possible for you to supply us with screenshots of these happenings? Feel free to send them to the support email; firstname.lastname@example.org and please reference with the following 'FAO Mark - Forum - Extra Tab at the End of Text File Rows'
Having received this information I can investigate this matter further and hopefully look to getting this resolved.
Having then tested this within the 7.2 build we can see that the exporting tools are exporting .txt files in the format of having return characters at the end of each row.
With this it makes it difficult for the import of these .txt files within Yellowfin as it is not producing a satisfactory pre defined configuration.
My advice would be to export to a .CSV file as this will then group the format in a way of it being more accessible and configured format or alternatively upgrade to 7.2 if you are happy to have the .txt files with the return characters at the end of each row.