I don't think any easy way is available to get the delta/impacted tables out of 56 tables.
A high level idea, you can improve it as needed
1. Create a sample table
2. check the impact on underlined HDFS folder whenever any DDL changes applied on it (or) if you can manage to capture the date/something else from descibe the formatted table before and after DDL change then it is good option.
3. Write a script and pass the 56 tables as a parameter. The script will simply describe the formatted output for the given table and idenfiy the impact compare to your previous X hour
4. Run the above script before you take a back-up every X hours