As can be seen from your screenshot, using the _Dir with all of your surfaces selected isn’t very helpful - the arrows just look like a big mess.
If you set up your display mode properly, you can quickly identify and flip the surfaces that are reversed.
Copy the standard shaded display mode and edit the copy to set the backface color to something that stands out (I’ve used red here):
Set all the layer colors to black:
Select all of your surfaces using the _SelAll command and set thier display color to "By Layer":
Now you can easily see which of your surfaces need to be flipped:
It took me about 5 minutes to manually select and flip the surfaces that were reversed:
You can go back to your original color scheme by selecting all with the _SelAll command and setting the display color back to "Custom":
Here’s your file after I edited it:
base - modela - one_re.3dm.zip (3.0 MB)