By the definition of the report.

I do not see what you are referring to. Such reports have maximum 4 context fields.
I mean that we have other information on the context that may be irrelevant for the report but we should include on the CSV header if we use a generic way.

This is exactly my proposal with CSV export.
Yes, the data is the same but there won’t be any header nor any footer on the CSV export. And I think it is important to have a proper header and footer for oficial document like balance sheet. For example, we may show on the header:
- The title for the report (Balance Sheet or Income Statement)
- The company name
- The title of the columns with the date
And on the footer:
- The page number (the report may fill up several pages so we must now if it is complete or not.)
Also the CSV export does not allow to customize the style which is important for some companies to produce more fancy reports: For example using diferent styles depending on the depth of the chart.

In the UK I think it depends on the type / size of the company, for example: https://www.legislation.gov.uk/uksi/2008/409/schedule/1/made
From what I understand what changes is the detail of the information. We have the same in Spain and we use two diferent charts to create a more detailed type structure. For big companies there are also more accounts required.