Yes, I think I get what you are trying to say and it's a valid point, just the words are a bit confusing.

So yes - 'most of the assets that back currency is just government debt' and 'much of that debt is held not just by the Central Bank but also by other government agencies'.

Which makes a good chunk of the system just a matter of accounting.

But: "balance sheets that really means very little"

No, it still means a lot.

Both the 'internal accounting' stuff matters, and you can't forget that most TBills are not held by 'other government agencies'.

Yes - the fact that the value of currency cay be 'fuzzy' is relevant, but it's not entirely fuzzy. All of that accounting matters still.