Inconsistent name wrt ISO 42010 and with its own definition - ArchitecturalDescription vs Architecture Description.
The multiplicities aren't correct. For example we have on Architecture to ArchitecturalDescription we have * on both ends which means that an Architecture has no existance independently of its ArchitectureDescriptions (plural as there have to be many of them). Should be 0..* on ArchitecturalDescription. Similarly with View it ought to be 1..* View and 0..* Viewpoint (otherwise an ArchitecturalDescription is required to include multiple Viewpoints which doesn't allow for a central set of 'library' viewpoints in ISO 42010 terminology).
The relationships with View, Viewpoint, Architecture need to be named.
'expresses' looks like a role but cannot be. If it is a role it needs to qualify the target element e.g. 'describedArchitecture' not the relationship.
Why does ArchitectureMetadata have a multiplicity of 1 on ArchitecturalDescription - is each piece of metadata unique to every ArchitecturalDescription?
What is an ArchitecturalReference? This looks like a relationship. What then is the point of adding a role name to a relationship? Isn't this just 'UAFElement traces to ArchitecturalDescription?