I started to point out that that one isn't correct either (notice how the back part of the E key is significantly wider than the back part of the F key, which i

I started to point out that that one isn't correct either (notice how the back part of the E key is significantly wider than the back part of the F key, which is wrong), but then I noticed that the article says this (mentioning me): "Update 13 October 2021: This method is great for getting piano key proportions very near accurate with a few very simple steps. Thanks to Rob Brown who added more details in the comments that will be helpful to anyone looking to make a highly accurate model (e.g. if you’re trying to align a drawing with a photo)" The actual proportions are described in the link above (I wrote a little algorithm to do it accurately for my music app)