The Episerver form submission data store into [tblBigTable] table the query which triggered on .csv download is similar to below:

You need to modify the query and use your own column (e.g. String04, String01 etc..) to fetch the data which you want to display.

 select  
CAST (R01.pkId as varchar(50)) + ':' + UPPER(CAST([Identity].Guid as varchar(50))) as [Id], R01.pkId as [StoreId], [Identity].Guid as [ExternalId], R01.ItemType as [ItemType],  
R01.String04 as "__field_48",  
R01.Boolean01 as "SYSTEMCOLUMN_FinalizedSubmission",  
R01.String01 as "SYSTEMCOLUMN_HostedPage",  
R01.String02 as "SYSTEMCOLUMN_Language",  
R01.Indexed_DateTime01 as "SYSTEMCOLUMN_SubmitTime",  
R01.String03 as "SYSTEMCOLUMN_SubmitUser"  
from [tblBigTable] as R01   
inner join tblBigTableIdentity as [Identity] on R01.pkId=[Identity].pkId   
where R01.StoreName='FormData_c8119de0-665c-431e-af5b-049112e99de2' and R01.Row=1

Also, The Episerver does not recommend to use the database directly to write the query for fetching records and display them. The best way to use IFormDataRepository (inside EPiServer.Forms.Core.Data namespace) to get submitted data.

If Above query fullfill your requirements then welcome!

Why not use the Forms Service API instead? 

https://world.episerver.com/documentation/developer-guides/Episerver-Service-API/episerver-forms-service-api/

Is there a way with this Forms Service API, to actually submit the form... put an entry in the CMS?    The reason why I ask is that we have a very highly designed form that might be difficult to break up but shouldn't change at all.