Well, for Space Engineers I get almost weekly an update, so they are still working on it I think. Yes it has bugs, but I think the game has certainly still a lot of attention of the developers. To medieval engineers... As far there is no multiplayer implemented, I'm not going to play this game, simply because it's boring as hell to just play alone.
Space engineer is supported well by his developers. One update each friday and they have great plan for the futur of SE. PLANET/OXYGEN
I just hope that ME won't be developed instead of space engineer. Like Mojang and Minecraft...
And for Medieval engineer, i don't know, concept look rly sexy, but alpha stage of this type of game are realy disgusting. So wait and see (aka steam sales )