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Inspired by an answer to When translating the law, who ensures that the wording does not change the meaning of the law?

When 2 different entities that speak different languages have a treaty, there are 2 versions of the treaty, one for each language. Has there ever been a case where one of the entities had their version of the treaty be substantially different from the "official" version by the other country, without knowing that the official version was different and significantly to their detriment? I'm talking both about accidental and deliberate translations.

Many examples throughout history but of the top of my head I can think of-

The Treaty of Wuchale between Italy and Ethiopia, where in the Italian version Ethiopia became a vassal or protectorate, but in the Ethiopian version they were more allies with the rights and privileges of a sovereign independent nation like foreign relations. The supposed breaking of which caused the First Italo-Abyssinian War.

Disputes over Article 17 regarding the conduct of foreign affairs led to the First Italo–Ethiopian War. The Italian version stated that Ethiopia was obliged to conduct all foreign affairs through Italian authorities, in effect making Ethiopia an Italian protectorate, while the Amharic version gave Ethiopia considerable autonomy, with the option of communicating with third powers through the Italians.1 The misunderstanding, according to the Italians, was due to the mistranslation of a verb, which formed a permissive clause in Amharic and a mandatory one in Italian.[2] Wikipedia: Treaty of Wuchale

There were also many cases when the Japanese invaded Korea during the 16th century (I think) where all the messengers in order to not offend the host and thus suffer bodily or business damage in the respective country edited the messages to be more polite or softer often completely negating the original meaning.

However, keep in mind I got these two examples from various places including the internet (I believe the Armchair historian and Extra Credits though it has been a while) but I did skim read in order to double check my memory.

Treaty of Waitangi (1840) between the British and Maori chiefs of North island, New Zealnd

Wikipedia's Treaty of Waitangi article goes into these differences in some details, noting that:

The most critical difference between the texts revolves around the
interpretation of three Māori words: kāwanatanga (governorship), which
is ceded to the Queen in the first article; rangatiratanga
(chieftainship) not mana (leadership) (which was stated in the
Declaration of Independence just five years before the Treaty was
signed), which is retained by the chiefs in the second; and taonga
(property or valued possessions), which the chiefs are guaranteed
ownership and control of, also in the second article. Few Māori
involved with The Treaty negotiations understood the concepts of
sovereignty or "governorship", as they were used by 19th-century
Europeans, and lawyer Moana Jackson has stated that "ceding mana or
sovereignty in a treaty was legally and culturally incomprehensible in
Māori terms".

More on this treaty can be found at the New Zealand History site.

UN Resolution 242 demanding withdrawal from the occupied territories in Palestine after the 1967 war. Wikipedia entry

The English text has a different emphasis on territories, some might fit, whereas the matching French text seems to imply all. Pay particular attention to Article 1, subpart i. Specifically, des territoires in French, would be better translated as the territories. No idea which text was closer in spirit to the intent during negotiations or whether any intentional duplicity was meant by any party. It's really a very, very, slight difference.

full text of both (PDF)

So Israel claims some withdrawal achieves compliance with 242, but Palestine claims total withdrawal is needed to do that. There's plenty of other stuff going on, of course, so I wouldn't overemphasize this aspect, but differences in the 2 translations do play their part.