Haven't run into this issue of leaving in original format (pref with T/N conversion but can do w/o) but been watching some dramas that arbitrarily uses USD (conversion isn't even accurate) and luckily numbers in hangeul sound a bit like chinese so I can tell. Still annoys me though.

Currency rates change all the time so it's best to leave it in its original form.

This, and (1) people should not be too lazy to use Google, (2) purchasing power of goods would likely have changed if the currency mention in the manga does not take place in the current year, and we would not expect translator to dig up exchange rates from say, a decade ago

Nulla in mundo pax sincera
"Always go too far, because that's where you'll find the truth." - Albert Camus

I would say in most cases, leave it as-is, and don't bother leaving a note, as that would slow down the pace during reading.

There are exceptions, though... for instance, one time I saw a manga which featured American soldiers... and they were talking about some new sneakers and how much they cost... and they said they cost a specific amount of yen. In this case, I'd give it a rough conversion to USD, just to make sense in terms of the the context with the characters, and make the line still flow naturally. Nobody cares if the conversion is entirely accurate, but I would definitely find it odd if american soldiers were conversing with each other about how much something costs in yen. Unless, of course, they were stationed in Japan or something. 🤣

Just be logical about it. 😮

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::End of Transmission::

Leave it in original form and add the conversion to Norwegian Krone lol mmm...

That meme is kinda dead now but it's really good when it last, but for general scanlation, I prefer to see it in original with conversion to USD, not because I'm from US but that's just the most universal currency we got right now mmm...

I will change this world mmm...
So the world can change me mmm...