They should be required to publish live spreadsheets on their websites showing their RWAs with daily marks. SpreadServe [1] would be perfect for this job.
Regulators in first world countries already require accurate and timely reporting. It's really not as simple as just publishing a data feed. That's why things like Basel II(+) exist.
The author is also using the word "spreadsheet" as shorthand to mean "the entire modelling infrastructure". For the trading book, this can be non-trivial.
-Banks As Secret Keepers: https://www.aeaweb.org/aea/2015conference/program/retrieve.p...
There's a recent but very influential paper that shows that banks need to keep their assets secret to function well.