I'm sorry but no, it doesn't work: where do you split the upper and lower surfaces ? In the attached screenshot, you can see that the upper surface goes to Z negative and then to (0,0). The point Z negative is an existing point in the coordinates list. The lower surface seems correct. Did you miss a i+1 or i-1 somewhere ?
Also: is it really necessary to have so many intermediate windows ? Asking about "." or "," separator is something that should be automagically checkable I think.
1) the first window is unnecessary: who in modern times uses Naca airfoils ?
2) import from *.dat or *.csv: you'll see when the user chooses the file, and/or check first valid line
3) line-numbers can be automatic, and separator should be also
=> 3 unecessary windows, you can go straight to #4
4) "Load File" should be called "Choose File" and lead directly (if successful) to #5 without clicking "Next"
5) "Close" should be "Cancel" and "Create Airfoil" should be in-line with "Back" and "Cancel": Back, Cancel, OK
5-2) Since the file is now loaded, it would be nice to show a preview of the airfoil
5-3) All the available options are not very self-explanatory
5-4) use of Qt .ui files is overkill for such simple windows. Did you try to build the UI directlly in the macro file ? Please find attached a similar macro I had made for my use that offsets airfoil curves in their own plane (figuring out atumagically its own plane), and that can also generate Sketches and Wires. May-be you can find some inspiration in the use of inline UI construction. It's also a good check that the airfoil you generate is correct as it will amplify the mistakes.