I think we're far too sensitive about saying things that might, possibly, if taken the wrong way, read on the night of a new moon when Venus is aligned the wrong way, offend. Blatantly offensive comments = clearly wrong. Politically correct pussyfooting = ridiculous. Our children will grow up not knowing how to approach a subject directly for fear of offending someone rather than able to treat things in a pragmatic yet sensitive manner.
And at cancelling the nativity play. Would they cancel a Diwali or Chinese New Year celebration on the same grounds? I feel that there are some things which, if you are offended by, you should remove yourself from. I object to the wholesale celebration and commercial glorification of Halloween. I could go so far as to say I'm offended by it. But I deal with that by removing myself from it, do not "celebrate" it by trick-or-treating or cutting up pumpkins and don't go around telling people how offensive it is.
Slightly off topic now...
Back on it - I agree the cultures probably would merge, hence my saying "as similar to their home life as possible" rather than a home away from home. But a childminder with ties to any culture is going to have more of an influence of that culture in their setting than a childminder with no ties to a particular culture, whether that be Japanese, Spanish or South African.
OP I hope you find a childminder you are happy with, who will support you in your efforts to raise your child bilingually with ties to your own culture and that of the country you live in. I think that is all anyone can hope for.
And apologies for ranting again.