Can't give you many tips, but just to say I feel sort of in the same situation. And that is without the language thing too. I find I am super nice and friendly and they are super polite, but pretty impersonal and really hard to get to know and share anything more than pleasantries. I guess some of it is a confidence thing for both parties. I am sure they are not thinking consciously of not taking you seriously though. You are not an imposter, I promise. I mean, if you are, who isn't? Sorry not to have more concrete acvice.
Try not to have conversations just about your child. Ask them about how they are. Tell them what you watched on TV. Ask them what they are doing at the weekend. Then remember what they have told you, and ask them if they had a good time doing xyz. Tell them funny things that your DD has done at home, Just make conversation basically. Build up a relationship that is not based solely on your DD. When you have got the lines of communication open it will be easier to get proper feedback. They will see you as a person and not just as a Mummy.
Perhaps you could volunteer to help on one of the nursery trips? YOu seem really happy with the nursery, so perhaps you could make a point of complimenting the food or saying how much your DD enjoyed a trip out. Maybe bring a small present (like a tin of biscuits) and a thank you card after they have taken her on a trip she has enjoyed or done something special with her. I got DS's key worker a box of celebrations chocolates after his first fully dry/clean day at nursery!
Remember that the some of the girls are very young and may lack confidence themselves. This can come across as them not taking you seriously (sideways looks, muttering answers to questions etc etc). I'm sure they don't see you as an 'imposter parent', although goodness knows most of us have felt that way from time to time.
its true that my conversations are just about dd, so maybe i need to just relax and chew the fat a bit. i always want to rush out of there because i feel awkward so i think i will try and mellow out.
the volunteering for a trip is also a great idea. i think i kind of overdid the biscuit/cake once when she first settled in so will wait for an appropriate time.
one thing they joke about is how many clothes and shoes my dd has, which is mainly due to my mum going potty spoiling her only grandchild. i must admit i got a little sensitive about it and try not to dress her so obviously PFB!
this morning there was a danish dad there for the drop off and he looked and acted as awkwardly as me so i guess i am not the only one . . . .