Above is the data, however the search criteria need to be exact.
I tried to search data and type in "AA" but it doesn't return result. It has to be exact type in "AAA"
Whenever you add any new column to the list, it will take some time to show the search results. But not too long, at after an hour you should able to see the columns. If this is not working you can try below idea,
I would say that it depends on the type of column that you are using and its metadata,
Microsoft says its primarily due to full-textQueryable need to be true. That you might need to check it out.
When you construct your KQL query by using free-text expressions, Search in SharePoint matches results for the terms you chose for the query based on terms stored in the full-text index. This includes managed property values where FullTextQueriable is set to true.
For example , in my case I have many content that has "Add" in it,
It might be Adding, Addition etc.
If you would like to display in your case you can search "AA*"
Using words in the free-text KQL query
When you use words in a free-text KQL query, Search in SharePoint returns results based on exact matches of your words with the terms stored in the full-text index. You can use just a part of a word, from the beginning of the word, by using the wildcard operator (*) to enable prefix matching. In prefix matching, Search in SharePoint matches results with terms that contain the word followed by zero or more characters.
For example, the following KQL queries return content items that contain the terms "federated" and "search":
KQL queries don't support suffix matching.
Please refer KQL Syntax Reference