To solve this properly you need to watch the event video. At 2:51 the fireworks give you the path to climb.
left right right left right left left right left
Once I got this, I looked up Percy climber disappear (since the theme of this box is disappearing) and came back with this page Percy Fawcett
Which at the bottom has a reference to the letter pictured above with the same wording.
That brings you to the posted answer "Percy Fawcett"
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