In this case, CafeTran 'assumes' your are trilingual and sets three languages for your glossary. You can remove the third language from Preferences > Definitions > Language column names.
Why would CafeTran Espresso assume that?
If you translate in three languages, you are likely trilingual. That's an obvious assumption.
I see that I cannot convince you :).
Well, that's not really a question of convincing me. Rather, that's what most users would expect.
Happy with the improved project templates feature but a little annoyed by the fact that languages of previously translated projects are added to the Definitions.
In my opinion this is contrary to the use of project templates, where the user defines everything, including the languages set in the project template.
I'd encourage you to reconsider this automatic addition of previous languages.
When I switch from an EN > NL project to a DE > NL project, both with their own project templates that contain the language combination, the DE > NL project lists EN as a language in the New Term dialogue box.