It's an API. There are many tools built on top of it, many with UIs. I'm sure they display things in many different ways for people internally and externally. The system I was working was back-end. It used negative numbers for debits. And it was really important you didn't confuse credit and debit numbers.
> Was that accountant fine with assets as negative numbers?
I find it hard to believe they didn't understand that's what Using negative numbers for debits means. They would be pretty aware that assets are debit accounts.
> The did have $1tn in their balance sheet. No DB, no CR. Just $1tn.
Did they have a complex balance sheet (I.e. beyond that just a couple of lines summary) with no columns? How do they represent a balance if you couldn't tell which were credits and debits?