Acorn
acorn.io
acorn.io
Even worse, they took CUE and created their own dialect while retaining the file extension. Their files are no longer valid CUE (if you use their "std" library and maybe some other things). Then they go on to say you're better off not knowing CUE, which I suspect will bite them in the arse.
I'd recommend thinking long and hard before considering this tool. Hope they pivot and I can re-evaluate them then, but they are off to a bad start.
Having looked at the product more, I can see how people are getting confused. You expose CUE without saying it. As more people continue to adopt CUE, they will see the CUE in acornfiles. It's obvious to anyone familiar with the syntax.
There are several other issues with Acorn that seem to go the opposite way the market is going. I'll not relay them here because the other places we've conversed make it seem like you don't want any feedback critical of your product.
Again if there's an Acornfile still called .cue somewhere, it's an oversight. You've pointed out an actual example now, so it's been removed.