For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
Not sure what you mean here, I looked at the page and whilst I've not counted all the values - the split totals do add up to the main total.Somehow it shows the total count of records on split while it shouldn't.