I didn’t run through all the details of your script, but I don’t think it’s a Dynamo issue. You’ll notice that the solids build correctly when your “Distance Between Stations” value matches the frequency in your corridor region (or a multiple of it). In your example, the corridor region frequency is set to 25m, so that’s why a 50m sampling distance works in your script. A distance of 25m works as well. If you change your corridor frequency to 20m, then a 40m sampling distance will work properly. So I think you need to make some adjustments to your script.
Also, I recommend keeping the geometry working range set to Medium instead of Extra Large since you are working in real-world coordinates. You will get the warnings in the script, but changing to Extra Large can create issues, as noted here: