Yes, and for the same reason.
The German diminutive suffix -chen makes the initial word neuter (and also adds an "Umlaut" on the root vowel if possible) [Think of "maid" in English for an equivalent initial root].
The Greek diminutive suffix -τσι also makes the original root neuter. The Greek suffix is probably less productive than the German one though.
Got a question listening to this exercise: it seems to me that when the last sound of a word is the same as the first sound of the following word, they "merge" as only one sound (we call these "diptongos" in Spanish). The last η from "Eleni" with the first εί from the "is" are pronounced as a single ee. Same with the next "a". Is it like this in Greek or is it because of the TTS feature? Thank you.
They do merge in way, yes, this is natural in spoken Greek. They are pronounced as a much longer sound. I don't understand what you mean by "Same with the next "a". " The merging can only happen if you have the same sound twice. Do you mean the αι > έ?
As a native speaker, I can tell that both 'eh' sounds were present are pronounced for example because of how elongated the linked syllables are. Otherwise you'd get Η Ελένη είν' ένα κορίτσι. And you'd also write it like that. :)