Julia mentions that the ransom note was written using "Baskerville font" which she said is very common. It is common but it is highly improbable that it would be ever used for a mechanical typewriter. Baskerville font is proportional (i.e., every character has different width) so it is not useful for the typewriter, especially the old mechanical one from the beginning of the twentieth century. Typewriter characters has to have the same width each, so non-proportional fonts (like famous Courier) are more likely to be used for them.
Dr. Ogden uses the term "teenagers" but that term didn't exist until the late 1940s.