For example, take a close look at the iPhone X in the "Device Library" list, the device and "notch" borders are butchered beyond recognition. A key component of the iPhone X's brand are the particular rounded corners used for the notch, and if the point of this project is to closely emulate particular devices instead of generic ones, it woefully missed the mark.
To be fair, I can't speak for the accuracy for the other devices included, but if their implementations are at all similar to the iPhone X's, I'd expect they are also poor representations.
Comparison between the CSS "iPhone X" and an accurate representation: https://notebook.barrowclift.me/dropbox/comparison.png, and a Light read for more information on the iPhone X corners: https://medium.com/tall-west/no-cutting-corners-on-the-iphon...
I understand your point of view, but I feel you're missing the purpose of these devices. The aim is not to provide a photo-realistic depiction of each device, but a representation that could be used on a landing page or a demo page.
We've found them to be adequate in situations where we require a responsive device frame, and I'm hopeful others will too.
Having said that, we will take another crack at the iPhone X to improve the shaping further. I think we can certainly get the rounded corners more in line with the actual shape. The notch may still be tricky though!