It only works online. You wouldn't want an online service receiving a copy of each of your DMs to classify language (which is required to figure out if translations is needed) and translate if asked. Most libre translate services out there are just tracking everyone to sell data to sustain the service.
you don't know what you're talking about. literally running it offline right now
do NOT start promoting dms in nostr as private or secure. that's been debated elsewhere. my god you are a king of red herrings.
NIP-17 DMs on Nostr are private. NIP-04 DMs are not. The debates have settled this.