No need to be sorry about anything. It was great, that you added this page. Getting the formatting right is tricky and requires a lot of experience.
I think PAGE_DOWN was missed. I changed it later. I don't think we have an extensive list of official keycap names, but it might be a good idea.
If you have any specific ideas for improvement of the guidelines (or anything else for that matter) let us know. You can use the talk pages for questions, suggestions and comments.