To improve classification results, please follow recommendations: 

• choose correct recognition languages (Setting > Smart gallery > Choose up to 3 recognition languages);
• keep the original photos on your device to receive more results.
  The classification uses only locally saved images (images from iCloud are not used);
• be precise while searching text on photos.

You can find more information about the classification in the following articles: 

How long does it take to classify photos? 

What types of images are used in classification?

What is the accuracy of the classification in FineReader PDF for Mobile?

Classification and recognition in FineReader PDF for Mobile

Why do I receive such broad search results in classification?