This was the official response from GW:
The supplement book's are no longer available and we have not been made aware of them getting reprinted or of any FAQ updates for them. However it does look like the digital copies of these two supplements have been updated. So if you have purchased the digital copies then you can get the updated information there.
http://www.games-workshop.com/en-US/Sen ... ok-Edition
http://www.games-workshop.com/en-US/Cla ... ok-Edition
The units most affected by the alternate rules in the Iyanden supplement underwent a significant change to their rules in the new Codex: Craftworlds. While these two books were not designed to work together as such, you and your opponent are welcome to use any rules you like in your own games, if you think it will lead to a more exciting mission. If you do own the Iyanden book, it of course remains a fantastic resource for background and artwork for an Eldar collection.
Should you have any other questions please give us a call at 1-800-394-4263 and we will work to get you helped out where we are able.
In other words, throw out your hard copy Sentinels/Raukaan book (and Iyanden if you have it) and pay for the digital version. Unless you have the digital one already, in which case you can just update it.
...and maybe don't buy any of these supplements in the future!
_________________Also known as Peter
- my record of painting and gaming in all sorts of 28mm games