They are unlikely to use a safety line while climbing the ratlines, unless the weather is truly terrible and in that case I assume the ship has an engine, otherwise it would take forever to climb up to the yardarms.
However they will use safety lines when working with the sails on the yardarms.
How do I know? Because most European countries with a seafaring tradition has a tall ship or two like this to train sea-officers.
It's not 1825, where the sailors and midshipmen had to climb and work in the masts in all weather.
In fact Danish sailors during the summer, didn't go down on deck unless they had to, like wash-day or Sunday-prayers. They slept in their hammocks tied to the yardarms and when they had to - ahem - relieve themselves, they walked to the lee end of the yardarm and did that. A bucket of water and a cloth would clean things... They of course also ate up there.
Yet, people rarely fell down.
Leonor will be fine. She will push boundaries by climbing the ratlines and gain more self-confidence and of course earn respect from her peers.