Hi Tamas, How are you?
Regarding your questions:
1 - The buckets of the type legacy will be deprecated very soon, we’re currently migrating buckets of accounts that still use them, since users need to sometimes apply changes to their application logic. The SDK will be supported until 2030, not the legacy buckets.
I just asked our CSM team to contact you to assist you through the process.
2 - It is possible to convert the legacy buckets to the new ones. The bucket must be empty before being converted, and after the conversion, the data can be restored.
I am sending you these Docs that may help you:
I hope it helps!