"No, I am sorry, good night!"
Translation:Όχι λυπάμαι, καληνύχτα!
When it comes to e's at the start and middle of words big part of it is just memorization unfortunately, but rules can at least help in the case of endings.
Ηη is the 'female e', if a word is female (η) and ends with an 'e' sounds it will almost always be η.
Ιι is the 'nutral e' if there is a nutral word (το) that ends with an e sound it will almost always be ι.
Υυ rarely aplears at the end of words.
Τhere are a couple of issues in this phrase "είμαι συγνώμη" The verb είμαι is the English verb "to be" and goes with an adjective or a noun, but not with συγγνώμη. Συγγνώμη means "I am sorry", not just only the adjective "sorry"=λυπημένος. "Eίμαι λυπημένος" means I am sad.
Confused, eh? No, it is too simple: I am sorry= λυπάμαι or συγγνώμη , but not είμαι λυπημένος=Ι am sad.
Now about συγνώμη or συγγνώμη: It means "I am sorry" for what I have done, but also "excuse me", asking permission to pass through, for instance. https://el.wiktionary.org/wiki/%CF%83%CF%85%CE%B3%CE%BD%CF%8E%CE%BC%CE%B7
That's not how Greek works (and that's a fairly strange question for level 12 in Greek:P)
Είμαι λυπάμαι is two verbs in a row. That wouldn't work at all, in syntax. This sentence's translation is not a word-for-word one. Being sorry translates to just λυπάμαι in Greek.