I once had an auditor tell me that the books are allowed to be wrong, but should be wrong consistently. I've even run into the timestamp issue, which generally turned out to be a non-issue unless the wrong date was used (like order date vs. shipping date for revenue recognition) or a considerable number of errors caused dates to end up in a different reporting period. If you're dates are consistently a few hours off, then they'll be consistently off across reporting period boundaries and that can easily be explained to an auditor.
> the necessity to batch reconciliation processes between these layers
I've never seen a reporting period closed without accountants making journal entries for manual adjustments. These can often be material changes.
> An accounting system does not convert currencies at will
This is correct, but for internal reporting you might need to. An accountant and cash flow will capture the important conversion rate when the funds are expatriated, but your finance dashboard showing sales in euros will have an executive that wants to see it in US dollars. It's impractical to use the conversion rate from the transfer that could happen weeks or months after the reporting period, so you come to a compromise of using a X-day FX moving average that's "close enough" and everyone's happy. What goes in your 10-K/Q will be a different story.