Actually $12.42 bn is the total FX fines paid: 24 of which were levied on 5 banks, the "cartel banks" totalling $12.270bn Most of the rest were for use of customer information to rig transactions.
This led to an erosion of trust in FX market among market participants who are now challenging each other. For example:
In the Mark Johnson case Cairn were saying that HSBC misled them
The Bogucki case where HP said Barclays misrepresented the market and did not disclose their own activity
The ECU Group class action against HSBC
As a result the FX market is having to become more transparent and many FX market participants have now committed to the FX Global Code.
The Code is organised around six leading principles with 55 principles of good practice. Generally it takes a mid sized buy-side firm 6 months to implement the code. The biggest work streams in most implementation projects tend to be staff training, and incorporating the code into internal documentation.
Because the code is principles based the challenge to incorporating the code into internal documentation lies in agreeing an risk appetite against each of the principles. Although many of those decisions can be relatively straight forward if you’ve implemented MiFID2 and MAR. Despite that many firms struggle with principles 11 and 17: pre-hedging (11) and last look (17). I think that is partly because the code is global and so the examples given in the code itself tend to be high level.