That is not spreadsheet risk, it's business process risk. You address risk by applying controls.
My old boss was a former labor statistician. His job 40 years ago was basically producing reports by having sets of data tabulated (aka "sending a job to a pool of people with big mechanical calculators") analyzing the data, and sending it somewhere else to be compiled into some report that was shipped to various places. They had people randomly sampling calculations for key or other errors. Other people were sampling the quality of his analysis and yet others were proofreading and double-checking the material prepared for print for typographical errors. The problem there was that building that process required thousands of people and a very rigid procedural setup to ensure consistency.
Computers changed all of that, and ultimately, all of that checking and re-checking was replaced by Excel. But that doesn't mean that you don't but a process around financial activities. You still need checks and balances.
All of these banks made decisions that speed to market for trading was worth the "risk" -- in this case that incompetent or malevolent traders can potentially put the bank out of business. The management accepts this risk because they don't bear ANY downside risk, as the bank is ineffectively regulated corporation. In the days when investment houses were partnerships, there were much tighter controls, as failure of the firm would bankrupt the partners.
They have a conference just about spreadsheet risk.