score:5
Your understanding is not correct, she can in fact enter Germany without a visa, like all holders of residence documents from Schengen countries. This is not based on the freedom of movement at all (which is why it does not require her to be with her husband) but on the Schengen Borders code, article 6(1)(b) and applies even to regular residence permit (i.e. for people who reside somewhere in the Schengen area as students, workers, etc. without any relationship to an EU citizen).
Technically, when visiting another Schengen countries, residence permit holders must fulfill all conditions for visitors (sufficient financial means, etc.) but there is even an explicit exception for transit: If you are travelling back to your country of residence (and can prove it with a ticket), these conditions can be waived. In practice, if you have a residence card for family member of an EU citizen, your rights are so strong that border guards rarely bother beyond establishing that you really are the holder of the card.
The example you noticed pertains to non-Schengen countries (there are hardly visible bullet points in the page) and is only valid there.