Why online? Why would I want some third-party to (a) listen to my conversations; (b) receive a copy of my voice that hackers could download; (c) analyze my private conversations for marketing purposes; (d) hobble my ability to translate when their system goes down, or permanently offline; or (e) require me to pay for a software service that's feasible to run locally on a smart phone?
Why would I want to have my ability to translate tied to internet connectivity? Routers can fail. Rural areas can be spotty. Cell towers can be downed by hurricanes. Hikes can take people out of cell tower range. People are not always inside of a city.
Hosting is annoyingly expensive. ping latency between us-east-1 and ap-southeast-1 is 230ms. So you either setup shop in one location or go multi-region (which adds up).
Also, there are many environments (especially when you travel) where your phone is not readily connected.
