According to this post, we should be using the Sdl.MultiTerm.Client.Api assembly instead of the older (now obsolete) Sdl.MultiTerm.TMO.Interop for programmatically accessing MultiTerm termbases.
However, I'm unable to find a method to browse entries (either at term or concept level) or to add entries.
The Sdl.MultiTerm.Client.Api assembly has a method on the Termbase class, GetEntry, which accepts the concept ID. But how am I expected to know the concept ID if I'm unable to browse the termbase?