True, but there's a big difference between dropping 38 basis points and losing 57% of its purchasing power.

[edit] more importantly, the yen may have dropped 38 basis points against the dollar, however that doesn't necessarily represent a drop in domestic purchasing power at all. Just foreign purchasing power. This change makes imports into Japan more expensive and exports of Japanese products denominated in dollars more affordable to foreign buyers. You're measuring apples vs oranges in that comparison.

Peak-to-trough, the Pound Sterling lost about 25% of its value against the Deutsche Mark during Black Wednesday. It lost about 30% over Brexit. The Aussie dollar fell about 35% against USD during the 2008 financial crisis. The Euro fell approximately 40% against the Swiss franc over the 2011 sovereign debt crisis.

So yes, "real currencies" can and do fluctuate significantly in terms of exchange rates. It simply makes no sense to contextualize exchange rate fluctuations as "annualized inflation".

To be clear, inflation isn't exchange rates. That's a change in how much you can buy in a foreign country with your currency - and how much of your goods they can buy with a unit of their currency, not how much you can buy at home.

Bitcoin's purchasing power fell equivalently the world over and so inflation is a more useful benchmark to compare the loss in purchasing power than foreign exchange is.

In most of those cases, you'd see similar declines if you benchmarked against a trade-weighted basket of G10 currencies.

Doesn't get more apples and oranges than comparing fiat currencies with hard money

Well that just sounds like a religious argument, no? Is there some basis on which you are making this assertion?