1. Hardly does Juan remember the accident that took his sister's life.
This sounds a bit odd to me. "Hardly" here relates to the degree of remembering; but it seems to me that when "hardly" fronts a sentence, it tends to have a temporal sense:
2. Hardly had the Prince touched the ground than he felt himself violently seized by an unseen power...
(i.e. the Prince was seized a split-second after touching the ground.)
So I would rephrase #1 thus:
3. Juan hardly remembers the accident that took his sister's life.
MrP