https://emedicine.medscape.com/article/964866-overview
Turns out you can be hospitalized for "just a cold sore", especially if you are a pediatric patient who is immunocompromised. Hospitals in Europe are more likely to hospitalize than US ones, and it is possible that the former au pair had other medical issues that she did not disclose. Immunocompromised runs the gamut. Recommendations for a child who is immunosuppressed from long term steroid therapy for asthma differ dramatically from one who has a primary immune deficiency, or is undergoing active treatment for childhood leukemia.
OP, I'm sorry you turned for support and found judgment. I use pro au pair. Much higher fees (sticker shock), and much fewer candidates. But they have nurses, physical therapists, occupational therapists, etc, depending on what your family's needs are. I wish you luck. I would have rematched over the hygiene alone in your situation, and as for HSV-1 issue followed the recommendation of my child's medical team.