Many thanks for the feedback, it helps to get things right

I have added some extra space for the label for the "Surface radius" field, this should allow the French translation to fit without running into the text field. There may be other labels like this, if you let me know I can try to accommodate.
Otherwise, I think the text (number) fields are sufficiently wide to accommodate number values. Please suggest improvements if required.
I think you will find the calculated surface radius is correct for a seed radius of 30, and a depth of 20 the surface radius is 32.5, this also matches the earlier provided Excel SS result. Did I miss something?
I think I have discovered the bug with the "Lines" - a trap for beginners (it was OK in English, but not on other languages

). Please try this new version out.
I have also fixed a small bug that allowed invalid surfaces types to be selected by default, if the current seed was different from the previous one.
Geoff