While being able to transfer ranks sounds great it would never work, certainly in your situation. You would for the very least need access to both accounts.
This also enables people to sell their rank to someone else, which is not something CubeCraft would want.
The best thing in your situation is to take account security very seriously. Think about the account security part of the
cubecraft safety guidelines. A password manager (like Bitwarden or LastPass).
Adding onto that, as you said ranks I assume you play bedrock. The purchases made are via a store managed by Microsoft, which means CubeCraft most likely cannot transfer purchases to another account.