Elementary OS is intended to be run on Macs or Windows PCs. Chromebooks are a bit different than the former and support in distributions may be lacking or incomplete, particularly for newer models. You may have more luck using GalliumOS or following articles in the Arch Wiki about Chromebooks.
Some of the features and configuration may be easy to port to your favorite distribution of choice, others may be more difficult. A newer kernel may help detecting the keyboard, but won't work well with non-Chromebook keyboard layouts. You could take a look at the respective GalliumOS packages (1, 2).
The guide you are referring to is from 2016 and if I recall correctly John Lewis hasn't updated his ROMs for a long time, while https://mrchromebox.tech/ is still active.