Thanks for creating these new support articles!
I haven’t had a chance to review the entire course yet, but as @kuovonne mentioned, the article “Common formula errors and how to fix them” doesn’t address the most common formula errors that we see on a regular basis in the forums.
Two of the most common errors that people encounter in formula fields are:

The formula box does not recognize curly/stylized quotation marks (regardless of whether the quotation marks are single or double quotation marks). The formula box only recognizes straight quotation marks. This is, by far, the #1 problem that people have with the formula box. There is no other problem that even comes close to the number of times that we see this problem.

The formula box does not allow spaces after the opening parenthesis of any function name.
So, for example, this formula works:
IF({Number Field} = 1, "Yes", "No" )
But this formula would not work:
IF( {Number Field} = 1, "Yes", "No" )
Of course, ideally, we would just clean up all those spaces anyways to look like this:
IF({Number Field}=1,"Yes","No")
But it’s good to let people know specifically where spaces are NOT allowed.