I heard it just fine.

Sounds like she cut of the final vowel and it was just "ikk".

Jenta is pronounced with 'full a' sound and jente is pronounced with 'half a' sound.

I may be wrong, but I feel like jente is pronounced more like yen-tuh and jenta is more like yen-taw.

https://forvo.com/word/no/jenta/#no

https://forvo.com/word/no/jente/#no

If you can't tell by the sound of the final vowel, you can tell by the context. The indefinite 'jente' needs an indefinite article 'en' or 'ei', and the definite form 'jenta' can't follow an indefinite article.

That would be a valid English translation, as far as I can tell.

"Jenta spiste ikke lunsj" if you want the past tense.

Hun spiser ikke lunsj. Norwegian doesn't have the simple present/present continuous like English.