I once worked for NEC designing PC's and my direct boss was Japanese as were most high level management. Anyway his command of the English language was generally excellent however there were a few things he said that would come off funny.

For example when he was confused by an explanation he would state "I am very confusing" as opposed to "I am very confused". We tried many times to explain the subtle difference between the meaning of these two statements but he never seemed to grasp the difference.

Anyway the reason for this long digression is that "I am very confusing" by the description of your problem.

First of all any technology advances are global in nature and so apply to all planets equally. In your example once you finish researching the technology "Xeno Research" then that enables you to build a "Xeno Lab" building on any planet that you own. One possible confusion is that there are some technologies that enable you to build one of a kind buildings which fall under the class of Super Projects, Trade Goods or Galactic Achievements (GA's are often also referred to as wonders). Anyway if it's one of these kinds of buildings then once it's queued up for production on one of your planets it's no longer available to build on any other planet.

As far as your example of "Soil Enhancement" that is something that should be available to build on any planet but only applies to tiles outlined in yellow that indicate they can be improved by this technology. If a planet has no yellow tiles then you can't build Soil Enhancement on that planet. Also you can only build Soil Enhancement on yellow tiles so if you have any other tile selected then you won't be able to select Soil Enhancement.

Finally the part of your description that makes me very confusing is the part where you say that some technology was completed by a specific planet. As far as I've ever seen in the two years that I've been playing the game, new technology is finished at the end of a turn and is based on the sum of all planets research during that turn. AFAIK there is no designation as to which specific planets research contribution actually "finished" a particular tech.

If you have a better building, e.g. Manufacturing Centers, and you are viewing the Old tab, you will see all the earlier buildings--Enhanced Factory, Factory, and Basic Factory.