Are you sure? I tried the link (which runs the entire page through Google Translate), and I tried plugging just that phrase into Google Translate directly, and they both translated the phrase correctly - "Silver Bridge".
And wouldn't "gold" be "or"? (of course, it's been a long time since high school french
You are correct, argent is of course silver.
I did not put in the phrase for translation, was just reading the translated page as you had linked it.
On that page "Bridge money" and "golden bridge are mentioned in two following sentences.
It is not an important point, just thought it was curious to see google translate in an incorrect way, while the topic was Untranslatable Words.