I am not clear as to what you did and what you are trying to do now. Realize that Apple IDs are separate items and it is not easy to transfer items from one account to another. Some cannot be transferred at all and some maybe able to be shared with Family Sharing. You say "iCloud+" but iClou+ is just an expanded version of iCloud. What is it you do not wish to lose - the enhanced aspects of it; files you have stored in it?
If all you had wished to do was use a different email address with your account, there was a MUCH simpler way to do that:
Here's how you change the email address you use for your Apple ID:
1. Go to https://appleid.apple.com and sign in.
2. In the Sign-In and Security section, choose Apple ID.
3. Enter the email address that you want to use as your Apple ID.
4. Choose Change Apple ID.
5. If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support
6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support
For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support
