Pretty small sample size.

Also, the nature of the tasks - appointments and such - are cognitively different from "note-taking" writ large.

Finally, the study used native Japanese speakers. Japan is significantly different from, say, the romance languages, both lexically and grammatically. There's no way to exclude the impact of these differences on the findings.

I'm not arguing against the general premise that handwriting facilitates beneficial cognitive processes.

I'm arguing that if you're not willing to report the findings in proper context, then you're not doing your job as a writer.