It's the same if they use one version or another, package builds anyway. Yes, we may build our own rpms. We the guys who know how to do it, we know what devel packages are needed. We have no problem. He using an experimental one.
Further versions are unsafe.
Download from rpm.org's ftp. The spec file doesn't even list it, I don't know why this is. If you download, build, and install it from the gtkhtml source though, Encompass will work. Trust me, it'll work, as long as the library is in the system. So, please try the new release, and try not to post information that isn't fully factual.