There are plenty of threads and lots of research in this area here at the Org -and some quite recent (last month) so you need to look a bit harder.
Oh, sorry. I searched on another forum. I will search here now.

But to save you some time - you cannot edit sounds attached to animations. And you cannot do anything with the descr_skeletons.txt file as it is not read - and cannot be used in generation - and the game even works without it I am told.
Ok, it's useful to know.
Thank you very much for your answer.