Thank you for the fast feedback. I didn't know about Help -> Debug Messages, it's very nice. The problem is that it's unlikely that new users will look there. :(
I only new that the "Terminal" was missing for me because the previous version (1.32) had it. Then when I installed 1.36 from source it didn't appear. Probably because a newer version of libvte that Geany started to use?
Then maybe lots of new users might not even imagine that they could have a terminal emulator.