Search node by Image Field and return image as result rather than the node
The problem you are facing is that Search API has a flat structure, so it cannot save multiple values for fields, as it would require a change in data structure which isn't done during indexing, since it will effect the already indexed results.

If you knew how many values you could get (fx max 3), then you could create entity properties that pointed to the values for image 2 and 3. Otherwise this is beyound the scope of what's possible right now with Search API module (at least to my knowledge.