If there were real issues with GDPR or the AI Act Apple would have nothing to lose and everything to gain by mentioning at least the generalities of _why_. But they did no such thing so we can only assume it is not any of those things which are the real issues.
Really? You can't imagine any reasons Apple wouldn't want to have a public PR battle about its disagreements with its primary regulator in the market? Have you ever worked with the government?
But for this translation feature they have not even mentioned any regulatory issues, so we should from conclude, from previous and current behaviour, that Apple is delaying for something else. Probably engineering or political reasons.
[1] https://www.macrumors.com/2025/09/12/apple-delays-iphone-air...
You have no source for this claim.