Here is the first article I found on the incident published in the Lancaster Intelligencer and Journal on April 30th in 1800 that relates an encounter with a sasquatch like creature in 1774.
At first I couldn’t find M. Le Roy or the forest of Yuary. But persistence payed off and I located the same account published 20 years prior in 1780.
The story is the same, word for word, but the preamble mentions the original publication the account was taken from. Memoir Sur Les Travaux, &c. Dans Less Pyrenees, &c.
The full title being, Memoire Sur Les Travaux Qui Ont Rapport A L’Exploitation De La Mature Dans Les Pyrennees.
M. Le Roy is Paul-Marie Leroy, a French engineer who had recorded the wild man story as it was related to him from the locals of the area he was working in.
Link to his wiki: Paul-Marie Leroy
The forest of Yuary is the Irati Forest or, the Foret d’Iraty if you want to get French with it. And the event happened near Saint-Jean-Pied-de-Port, France, where the locals reportedly saw the creature often.
Was it a case of abandonment of a child afflicted with hypertrichosis, a condition that causes excessive hair growth all over the body including the face? Lacking social interactions a person would undoubtedly become feral.
Or was it the real deal? Last of a dying breed maybe, on the European continent.
Wild men, woodwose and so on, have been depicted in European art and lore since at least the 12th century. With similar references to hairy human-like creatures popping up all over the world.
Do with this information what you will.