With the serial numbers and massive storage all they’d need is a pathtracking software and to standardize scanning bills to create records at POS.
Sure there’d be gaps but this’d be automatable, so no more FBI agents in a room copying serial numbers to avoid marking the bills. Then whenever voxel scanning happens a bank worker could scan a whole palette of currency and record its data.
So not 100% but significantly more than previously.
The issue is that there are plenty of transactions outside of the jurisdiction of the country. More than half of the physical currency supply in the US is outside of the US, and while the Euro has explicitly made this possible from the onset, I don’t think nations outside of China can have a complete enough picture to trace everything.