I like that polish has phonetic spelling, most of the time. I know in polish, un-phonetic spelling is used for comic effect by one of the characters in włatcy móch.
We really need spelling reform in English. English spelling made sense 600 years ago, but the language's pronunciation has changed so much since it's spelling was standardised a long time ago. It made reading very hard for dyslexic people such as myself.
It does sound weird indeed, something between 'g' and no sound at all. So it's a voice mistake. It's a looooooot more probable that there's a voice mistake than a word having vanishing sounds. Polish is 99,9% pronounced exactly how it's written (when you know how different letters are pronounced, of course). Well, there's also devoicing, but we don't think about it, it's rather how it turns out in real speech.
It would be an infinitely more likely sentence to say, but it's not a translation. "Ona jest córką" without stating 'whose daughter' does not really make much sense. Probably at this phase of the course the possessive pronouns were not introduced yet, but it doesn't change the fact that the sentence is very clumsy.