I think you should generate an interop DLL from SEPreview.tlb giving the interop DLL created a unique identity. Then deliver the interop assembly with your assembly. That way you don't rely on the file being delivered by Edge (or any changes that might cause an issue).
I believe ST4 has a GenEdgeInteropAssemblies.bat file under the sdk that generates interop assemblies. It does so for the commonly used .tlb files. You can modify it to do so for SEPreview.tlb. Just copy one of the lines, say for framewrk.tlb, and replace "framework" with "SEPreview" where you see the namespace entry. If you have reached into the program folder to reference the primary interop assembly there (looks like it since "Lib" is part of the name), the namespace you generate can avoid compile errors.