Looking through the forum and bugs category there does not seem to be anything about Custom Fields from the Credit Notes module not being populated in the General Ledger Transactions in Custom Reports. This can be seen in the picture where there are no fields for Credit Notes
Also, in General Ledger Transactions in Custom Reports, the Customer and Billing address fields for Credit Notes do no populate in the records as other Credit Notes fields like Account, Description, Qty etc.
Custom fields in Customer module do populate in Sales Invoice records but do not populate in Credit note records in Custom Reports when General Ledger Transactions is selected. An example of such Custom Field is “Note”
As you have been told before, custom fields are a work in progress. Not everything is exposed. End of discussion.
The fields available which you have mentioned are line item fields and have nothing to do specifically with credit notes. Things specifically related to credit notes are in a different table and derive from the sales invoices module.
See #1 above.
Complaints about custom reports are really a waste of your time. They are not finished and they are not documented to any great extent. The developer has announced they are being extensively revised.
@Tut sure I know custom fields are a work in progress and that is why I wanted to point this out for the record, only suggestions and far from being a complaint. It can also benefit other Manager users if they search the forum quickly to see what is pending and save time in testing in software if something does not work as expected.
Good to know custom reports are being extensively revised as they are very useful
Items nr 1-3 above for Credit notes in Custom reports have been fixed