OP, firstly most children go through this. I would try not to overthink it, and truth be told, there will be days when she doesn’t say or appear to remember anything, and then a few days later it will come out that “when me and ex were playing on the slide we ….” And it will be an event you had no idea about and which she won’t remember she didn’t tell you.
Secondly, I would keep her in the preschool if there is a language barrier. It’s hard to think of it now, but if you’re planning to stay there permanently or at the very least in the long term then it’s important that she learn the language as soon as possible, and being immersed in that language is the perfect time to do it, however hard that might sound.
Give it 6 months and she will likely be fluent, but she’s only going to achieve that by being exposed to the language in question.
FWIW I speak as someone who moved abroad aged nine and who was sent to boarding school where I didn’t speak their language and they didn’t speak mine. Within 6 months I was fluent, and within 12 months you would never have known I wasn’t a native speaker.
I took the language as a 1st not 2nd language in my exams, I lived breathed and thought in that language, and even though I’ve been back in the UK for 28 years now I can still speak it as if it were a 1st language, and friends I speak to over there say they would never have guessed I’d spent the past 28 years living back in the UK.
But that wouldn’t have happened if I hadn’t been thrown in at the deep end.