I don't believe Adobe can transfer your Library/ Catalog from one account to another.
I can only think of two options at the currently.
You could would need to export everything, either manually or using the Lightroom Downloadet tool: (https://lightroom.adobe.com/lightroom-downloader). The trouble with this is that although RAWs can/will be exported with the sidecar settings, the JPEG's will be exported with amends applied and on re-import you will no longer be able to revert to the original.
Another option would be that if you use Lightroom Classic would could sync everything down to that. Now, I'm not a Classic user, but then somehow you could resync Collections to the new Cloud space and once the Smart Previews are in the Cloud (as Classic can only sync these lower res proxies), import the Full Res into the Cloud Based Lightroom which will overwrite the Smart Previews in the Cloud.
This way the non destructive edits should be retained but you'd need to be au fait with Classic though and play around with a few files to see if it works.
Since I don't use Classic, I have tried to use the Lightroom downloader. It took a while, but all my photos are now uploaded to my new profile. Unfortunately this has left me with quite a job getting my photos reorganized in the right order/albums. Do you know of any smart way to do this...?