No, not you are all, it's you all are. Think y'all are Dutch rather than you are all Dutch and you'll get the word order right. The two sentences mean different things.
You all is accepted because a large enough group use it to warrant its inclusion. All sentences that use it should accept just you, as most English speakers don't use you all for the plural you.
It could also mean that though the direct translation for that is.
You are all dutch Nyinyi wote ni waholanzi.
First of all the spelling should be "nyinyi" and the correct translation is you are all Dutch.