My experiences so far now I am nearing the end of the course I asked about in the OP. I am doing German - so I will comment on how it worked out. I daresay other courses will follow a similar format.
The course is conducted over Zoom with 11 other students and the teacher. We also have text books (a book with course material and a book with exercises).
The teacher we got is quite well organised - she has a series of Powerpoints / PDFs summarising the material for the lesson to screenshare when necessary - these are emailed to us at the end of the class. The oral parts or where the class has to do some exercises are done either with the whole class in the main "room" or with smaller groups in "breakout" rooms. Sometimes we get difficulties with people losing connection etc but for the most part it has worked out well. The teacher makes sure everyone gets a turn if we are going through some oral work.
Homework is mostly from the exercise book - with the solutions at the back so we can self-mark. We also get written exercises where we need to write a small piece of text e.g. a letter or an article. In this case we scan / email our work to the teacher - she marks / corrects and emails back.
My experience has been positive enough that I have signed up to the next course. The only thing now (20th April 2021) is "BAG" have said classroom learning for adults can now recommence and the teacher said MKS are now pushing to get people back into the classroom. The first problem is our teacher and her husband are in the high-risk group for Covid and not yet vaccinated - plus as an asthmatic I don't really fancy the journey on a crowded bus to Oerlikon at rush hour. I get my vaccinations soon - so this might be a moot point for me, but it could mean the next course does not go ahead if they cannot get a teacher. As it is, most of my classmates have signed up for the next course, and there was a unanimous vote against a return to the classroom - and the teacher was going to make representation to MKS on this basis. If you book onto a course, you might want to pick a location that is easy for you to get to in case they switch from online to classroom.
HTH.
Nick