“Native Americans” is not one culture…it is many, and they are very distinct to one another. It’s a bit like saying, “Is anyone from Europe, who can help us translate into a European language? We are writing a story that involves a culture akin to Europeans.” Or central Africa, or any other large region with multiple tribes and ethnicities whose beliefs and cultures vary widely.
One of my favourite blogs (well, Tumblrs really) is Writing With Colour. They have a First Nations tag, which I highly recommend and which may be helpful to you. Here is a link to their First Nations posts, which might be very helpful to read.
There is also this post, with some suggestions about writers who wish to use elements from, or write about, a First Nations/Native American culture. And the ask tag contains some links to other blogs as well.
Also, if you google a particular language (the Cherokee Nation website has a searchable lexicon, for instance), that might give you a good starting point for research until you are able to find people from the appropriate tribe to help beta the appropriate sections.
Same with the traditions–Google is a wonderful starting point, and then I think you can also find people from the applicable nation who are able to answer specific questions you might still have after some research.
I hope some of this is helpful!