It was last updated in May. I don't know where you see a year but look at the commits: https://github.com/naturalog/tauchain/commits/master

Development is not going to be fast until the compiler is complete and the compiler has to be correct by construction. It cannot have a bug and must be built in the formal way. In addition, it must be as optimized as possible. The developer is working with all of the state of the art concepts and ideas so it's something which can't be developed any faster no matter how much money you throw at it or how many Phds you have.

But I do think once the compiler is complete then anyone will be able to join in and development will be significantly faster. The question of how long it will take to complete the compiler is anyone's guess but only Ohad has any idea. I thought it would be completed by now but the only answer I can give now is as long as it takes to get it done right.