The attached .tdl is complete rubbish, just used for testing in v7.0.x.
This shows my export settings.

In the "Exporting Csv File" dialog (CSV should be caps on that page) shows comma for delimiter and the "Always export..." is checked.
The task attributes are shown here, compare to the import below.

Excel is launched (I wish it wasn't) and no changes are made. But note that there are no column headings for time units.

Wait a few seconds to avoid file lock issues, then Close Excel.
Now go to Import Tasks, set file name. Note the initial state of the task data.

Note import fields with no mapping to target attributes:


Here is the result.

1) New ID 226 from 9 removed leading empty lines from its rich text comment.
2) New 227 from 8 has all of its embedded images removed from the comment, and the remaining text is also moved up.
3) The order of Level 2 tasks 223,224,225 is different from the source 4,13,14.
4) Other level 1 tasks are ordered differently.
5) After an import the "file changed" asterisk on the list's tab is removed.
My original notes about mis-ordering were due to the list being sorted by a field other than the position, so it's not as bad as I thought. But this test was done with tasks sorted by position, as shown. I'm not sure if that's a factor.
HTH
T