You can definitely use y-utilities in production. Although it’s quite new and untested, I’m fairly confident in the implementation and I plan to fix bugs when they pop up. In the future, I plan to introduce another Y.KeyValue data type to Yjs that will exist alongside Y.Array and Y.Map. The KeyValue type in y-utilities package fills the gap until we get there.
To be explicit: Y.KeyValue (which doesn’t exist yet) will definitely not be compatible with y-utilities’ KeyValue type. However, you can continue to use them alongside each other.