Shortly before he died, Professor Barker set up a non-profit corporation called the Tekumel Foundation to care for his Tekumel-related intellectual property. Its mission is to preserve his creative vision, and to act as the licensing authority for anyone who wants to use his work in new publications or other media. The Foundation is the group trying to get the novels available as ebooks.
Apparently the Foundation was set up with very little capital. Rumor has it that most of its funds were used on legal fees to get Barker's contracts and copyrights cleared up (so the Foundation can safely issue licenses for new publications), and for preserving his archive (lots and lots of Tekumel material). So now it's basically a small group of volunteers. They don't seem to be able to get anything done very fast at all.
You are welcome to try to contact them and volunteer your assistance.
http://tekumelfoundation.org/Their blog is where they post news:
https://blog.tekumelfoundation.org/