REST maturity levels and DDD are orthogonal concerns.
Your Ubiquitous Language doesn't care whether it's reflected deep down in the payload of a SOAP message, in a resource URI, or in a domain-specific content type, as long as it remains pervasive and coherent throughout its Bounded Context.
If your Bounded Context includes both the client and server parts, HTTP will inevitably stand in your way, breaking the semantic continuity between the client and Application Service. If you adhere to the First Law of Distributed Objects, there's no way around it. When reading or programming client code, it will never be as fluid and easily discoverable as calling a method named after a domain concept on an object named after a domain concept. There will always be an impedence mismatch between the HTTP protocol commands and your domain verbs or commands.
If the BC ends at the Application Layer and/or acts as a Supplier or an Open Host Service to other systems, HATEOAS might provide a more clearly expressed and discoverable Published Language (in the form of a Domain Application Protocol) than the other levels, with less effort. But well-documented level 0, 1 or 2 implementations can remain perfectly valid depending on other contextual criteria.