He donated his clothes in goodwill.
I think the English translation here is incorrect. Not ‘in goodwill’ but ‘to a charity’ (as ChatGPT in the Explain function explained). ‘Association caritative’ in French means ‘charitable organization’ according to Wiktionary.
Agreed. By the way there is an organization in the US called “Goodwill” which takes clothes donnations.
In US English, the word “goodwill” has become synonymous to “charity organization for donating clothes”. So the sentence would have been correct and natural if it said “He donated his clothes to Goodwill” (You can find a reddit discussion of “How do I donate clothes to Goodwill” for example)
Still the sentence should be corrected to say at least “to goodwill” because “in goodwill” doesn’t match the French sentence.