FreeSCI is under active development, and has been under constant development since it's beginning, so don't worry! There just haven't been any public binary releases lately because the current new versions are only development versions.
You can always download the latest daily source and compile it yourself. If you don't know how to compile it, you could nicely ask the maintainer of the port for your platform for a binary.
There are no interpreters other than Sierra's which run newer SCI games, but there is development on decoding and tools for newer SCI games, and FreeSCI have plans to continue development, and when SCI0 support it complete, move into SCI1 and possibly more.
