Hi - thanks for that vote of confidence wish I did know as much as they do. I also had problems with Custom Specifics but my was on my end.
That is weird and to me it sounds like a technical problem on their end.
I do now you can't write anything outside some of the boxes. For instance when in Main Color, did not use their drop down color and wrote in say turquoise, it dumped it. You have to use their colors (which sounds like you did).
The old specifics do carry over. However, I would test a couple first because I have not done the old in a week or two. Also, the old ones that have writing outside of their boxes are not always converting over. Say if you have main color and clicked other and put in pink and blue. On most listings the pink and blue will not flip over to ebay. So if you have some inside of the boxes they were moving over a week or two ago.
I do not know how this works if acutiva ends the use of the first option though. I assume they will have set up system to convert them, but do not know that for sure.
I changed a bunch of my listings to the new, it was time consuming process. If you change it be sure to clear out the old one, it will not work with both filled in. There is little box on old that says CLEAR do it there. I am sure you already know that but someone may not.
I am now doing all of my new listings with the NEW form though.
Not sure if this helps, it should like you are doing this the right way.
When you write support always have your cookies and cache cleared and let them know on first support request that you have done that. Most of the time that saves a step back & forth.
Sorry, wish I could be more help. . will check back later if you have other questions or that I missed something.
Vickie