You will need to rearrange the JSON somewhat.
Firstly, if you are using CSV, note that CSV files can only ever represent a single sheet. They have no concept of multiple sheets, you need multiple CSV files. You can use Excel to combine those files, especially if using newer versions of Excel. If your version of Excel has PowerQuery included then automatically combining a folder of CSV files into a single workbook is pretty easy. Even if not, it is relatively easy, especially with a bit of VBA for automation.
You could also do the automation using PowerShell if you are on a platform with support (it is available on Linux not just Windows these days). Because PowerShell supports .net natively, you can use the Excel libraries to combine data.
