Hi,
I don't really see the problem.
I'm able to edit the variants, enter text in the HTML editor of the description and custom fields there, and then save. And when I edit again the variant I do see what I entered in them, each time I edit them.
What I found though is that because there are 4 HTML editors on the page, and JCE Pro has a lot of things to do to initialize itself, it takes a while for it to finish initialization and the editor interface only displays after about 10 seconds, which is quite a lot.
Now, this is with Firefox. With Chrome, it's quite a bit faster and I actually didn't notice the slow initialization before I switched to Firefox.
Maybe you thought it didn't work because you didn't wait long enough to allow Firefox to initialize the editors ?