Actually the free tier is a pain - you need to put in credit card information, and they'll charge you if you go over a threshold. You can probably put limits on your keys to avoid that, but I don't think we should expect any users to need to risk paying for stuff for inbuilt Composr functionality.

Better to consider integrating other translate APIs, here are the options I've found:
- Microsoft (best choice IMO)
- Yandex
- IBM Watson (I don't trust it to continue to work reliably TBH, as it's translation API is a minor player)

Currently the 'translation' v11 unit test is failing as our free Google API year expired.
I plan to fix that by making the Composr v11 translation API support multiple backends, using hooks, as I did for the weather API.
I'm not sure what we'll do with the Google part of it - probably I'll keep testing working by moving our API key onto a paid tier with low usage limits, so it doesn't trigger a fee.

The v3 API requires 'service accounts', not API keys, making it more complex (asking anyone who's not a programmer to setup service accounts is too much IMO, especially because with API keys we can share a key across multiple APIs). It is also still in beta. So we can forget that for now at least.

Bing Translator support is now added. So a user can choose between Google Translate, or Bing Translator.