For those having the same issue with WAB, here is a working solution:
1. Create a custom Python script to iterate through your table and create field aliases for each field; you can use arcpy.AlterField_management for this purpose (make sure you skip required fields, such as OBJECTID, Shape, Shape_length, Shape_area etc.).
2. Publish your data as a service.
3. Create a webmap from your published service and enable popups (they will be automatically generated based on your field aliases).
4. Launch WAB Developer with the new webmap and you should have proper labels for your infographics (based on field aliases and not field names).