I did not read any "terms of service" of google, however as mentioned above (in this replay) I want the downloaded files for personal non-commercial use, so I doubt google would object.

Just a suggestion. You might want to actually look into Google's terms of service (and other information) and re-evaluate your conclusion.

• Google Translate API Terms of Service
  • Excerpts:
    • "The Google Translate API is provided to you without any free usage quota at all. You will be charged for each successful request you make through the Translate API."
    • "You may not access the Translate API in a manner intended to avoid incurring fees."
• Google Translate API FAQ
  • Excerpts from answers:
    • "No, the Google Translate API is only available as a paid service."
    • "The decision to deprecate the API and replace it with the paid service was made due to the substantial economic burden caused by extensive abuse."

My personal impression is that you will not able to use the Google Translate API without paying fees. And if they changed to a pay only model on the API, I wouldn't be surprised if they may also decide to try to detect and possibly block attempts to automate their web interface to their translate service.