This self-paced interactive course is freely available on Wolfram U and you can get a certificate of completion or a level-1 certification. See the course catalogue for details information and link to access it.

Not yet!

I have started a couple of weeks ago, doing the units in sequence. I watch the video, then read the compagnon notebook (redoing and toying with most of the given exemples), and finally answering the exercises.

I have completed units 1 to 19 so far, although I have a lot of trouble with the automatic grader for this unit: only one answer out of 15 was marked as "correct"! Which is unexpected since even question 12 is marked as incorrect even when using the code given in the video! In other words, even the solution provided as an exemple of question 12 in the course does not work!

Nevertheless, in my opinion, it's a good training that allows us to explore the many facets of the Wolfram Language.

What is your experience with this course?

Yes, you are probably right in assuming that an LLM is at work here. My guess is that some updates have not been made to the AI or that some changes have been made to WL that have broken the grader on this specific chapter about dates and times computations.

only one answer out of 15 was marked as "correct"! Which is unexpected since even question 12 is marked as incorrect even when using the code given in the video!

I'd suggest consulting the answers chapter in the book. The course is based on a book with the same name (completely free, of course) and with the added bonus of a chapter for answers. However, despite the exercises being largely the same, there might be some misalignment across the two. So, it might be a good idea to open the chapter at hand on the book as well.

All this aside, it usually has been the case for me that I was misinterpreting the question or the exercise and the code I provided was deficient in some way.