@uhoh A user spent on a bounty and got no answers, which makes me feel sorry for the user. Maybe as a new site we just don't have enough users from a broad enough range of fields to answer every question. I searched "LEED" on our site and found that you had asked some LEED questions too. Would you be able to take a shot at answer this one? You'd probably be the only answer being considered for the bounty:

I think there are very few people on Earth who actually do the full dynamical diffraction for LEED, and few-squared of them have heard of Stack Exchange. :-)

It would be better to get some people together and make a modern Python package from the old codes laying around. I've left a comment there to this effect. Thank you very much for pinging me!

@uhoh And of the "few people on Earth" I found two of them!

No I don't think either of us do that, though likely we'd both like to.