Is it possible to place a reward in the spire or crafting in the magic academy, to evolve any event building? I have buildings in worlds that may only have level one, six or even eight I can't evolve to level 10. Buying them is not an option as I spend enough on this game as it is.
Terminology is such a problem. An "event building" is not the same as an Evolving building. The Evolving buildings, as I think you mean, take "artifacts" to up grade them all the way up to level 10. It takes 9 artifacts to get to level 10 since the building starts on level 1. An event building takes Royal Restorations to upgrade it and it can be upgraded once each chapter you complete or are in (in other words if you are in chapter 10 and got the event building during an event when you were in chapter 8, you could use royal restoration spells to upgrade it twice. Once to chapter 9 level and once to chapter 10). I think you were speaking of Evolving buildings and their need for the right artifact to upgrade them. Most artifacts are tied to a single building and you need that one to evolve it once (you can also upgrade Evolving buildings them, but that doesn't have an impact on their evolved levels, only their base production. Whew! Confusing? You bet. In any case event buildings and evolving buildings can both be upgraded but only Evolving buildings can evolve and it takes the right artifacts for that.
As mentioned, artifacts, once the event where the evolving building was offered has ended, the artifact can be found in the spire, in crafting, and in the next FA (I may be wrong about the FA but if so, just blame my old age, it gets blamed for everything I do wrong). Unfortunately, in the Spire each artifact is only offered for a few weeks every 2 years or so since there are so many. Ditto for crafting. So if you see one you need, grab it!
Hope this helps.
AJ