Built-in translation issues on macOS 27.2

The behavior you are describing—where the window briefly loads, fades away, and displays the "Translation is unavailable" error—points to a conflict with network proxies/VPNs.

Because deleting the language packs only resolves it until your next reboot, a system process is breaking upon startup.

Check for Network Proxies or VPNs (Most Common Cause)

Recent macOS updates have introduced strict restrictions on system translation services. If you use a system-wide VPN, an encrypted proxy, or an advanced firewall/content blocker (like AdGuard or Little Snitch), it will immediately break the online translation service. 

• The Test: Turn off your VPN or proxy entirely.
• The Fix: If the translation works when they are turned off, you need to add an exception rule in your proxy/VPN client to bypass or "direct-route" Apple’s translation servers (*.apple.com and related translation endpoints)

More info from Apple: Modify or remove a VPN configuration - Apple Support

Commercial VPNs fall into the category of crapware. That includes:

• Cleaners (software claiming to automatically free up space)
• Optimizers (software claiming to make your Mac run faster)
• Antivirus software
• VPN software (unless provided by a school/employer to enable access to internal resources from a remote location)

Such 3rd party system ‘helpers’, ‘cleaners’ and ‘protectors’ do more harm than good. In fact, such products are completely unnecessary for macOS and the only ‘good’ (if you want to call it that) they do is to put money in the developers’ pockets. Cleaners and protectors cause compatibility issues, often after macOS updates. Commercial VPNs claim to hide your browsing activity from websites, and while that may be true those VPN providers just sell your browsing data to others. For the user, all of these types of software offer only harm…and if that is limited to harm to your bank account, then count yourself lucky. If you have installed such software, follow the developer’s instructions to completely uninstall it (note that some developers fail to provide instructions and their software installs can be pervasive, meaning the only way to truly remove it is to erase your Mac, reinstall macOS then restore your user files from a backup).

Hi,

Built-in language translation issues on macOS 27.2 are often tied to conflicts in your Apple Intelligence and Siri language settings or leftover offline translation packs.

Fixing Translation Issues on macOS 27.2

• Check Siri & System Languages: Go to System Settings > Apple Intelligence & Siri. Ensure your preferred responses and Siri languages match your primary language, as mismatched settings (like leftover French defaults) break translations. Change them to your preferred language and restart your Mac.
• Reset Offline Translation Packs: Navigate to System Settings > General > Language & Region. Look for Translation Languages or Downloaded Languages. Remove any corrupted language packs, restart your Mac, and re-download the correct language data.
• Verify System Language Support: macOS 27.2 expands Siri AI and system language features (adding support for languages like Japanese, French, Spanish, Portuguese, and Korean), but your primary system display language must match a supported profile for on-device translation frameworks to route correctly.

Thanks a lot for the advice — it helped! The problem turned out to be caused by LuLu. Disabling it makes the built-in translation work again without any issues, and the audio playback problem has also disappeared.

I totally agree with your point of view regarding crapware. However, I've found LuLu quite useful because I need to block certain processes and apps from accessing the Internet. I don't normally use a VPN for everyday browsing, but sometimes I have to use one to get around IP-based restrictions. Any else crapware is an absolute crap! 💯

Thanks again for your help! Now I'll try to figure out which processes LuLu is actually blocking.

Finally solved!

I updated the app, as for some reason it had stopped notifying me when a new version was available.

It also seems that the app was disabled as Network Extension in System Settings. I enabled it, and now everything works fine!