Please take a look at our documentation:
smart search transformation
The issue is, that the smart search result data set contains a limited set of data, compared to a repeater, containing all document (page) fields. You need to use the GetSearchValue method, instead of the Eval method for some of the fields. You can find the data columns, which you can access directly with the Eval method in the search results transformation in this article (sorry for the low quality image):
custom data in smart search transformations
So, you can use Eval("title") or Eval("score"), but for other fields, the GetSearchValue method needs to be used, as per mentioned documentation.