We just went from absurdly insanely hard task, to a task I'd guess a thousand times harder. A communicator and observer probe is almost impossible enough, but to additionally preserve biological tissue for thousands of years in space is even harder than sending pure robot. And then terraforming part is just orders of magnitude harder than that. Communicator probe would be a few thousand tons maybe and packing maybe a few megawatts of onboard power. Lets be generous and give them a thousand times more - a few gigawatts, provided they are magic aliens and stuff. What can you terraform on a few gigawatts? Raise a temperature in a ten meter circle by one degree? Produce a few cubic meters of something from atmosphere? To terraform one would need a giant fleet of giant vessels, all fine tuned for some processes, and then they will work for millennia to change planet a tiny bit. We would notice that kind of operation in the Solar system.

I love LeGuin, Reynolds, and other, sci-fi is practically 90% of what I'm reading. But come on, the whole interstellar stuff is always predicated on very very optimistic assumptions and eventually magic.