I wasn't able to report it at the time because I was doing a timed practice, so I'll report it here. I got this sentence as a multiple choice exercise and selected "Ana este la bucătărie." and "Ana se află la bucătărie." I happen to know the verb "se afla" but it hasn't been introduced in the course. I don't know if selecting just the first sentence would count as a correct answer. I experienced a similar problem in another exercise (can't remember which) that had the word "arahidă" (which was introduced), but it also required me to select the option with "alună" (which was not introduced). I hope this issue can be resolved. Anyway, thanks for your amazing work!
The native speaker is right, of course. But languages don't use the definite article in the same way. English needs “the” when referring to rooms in a house (Anna is in the kitchen), but other languages like Italian and Romanian don’t (Anna è in cucina / Ana e la bucătărie).