If the only explanation was that they were catching far more low-grade symptoms, then we should see a lower CFR with the resolved cases rising rapidly.
I hope that what you state is the case, and their CFR remains where it is while the number of recovered grows. But it's still an unknown, and we won't actually know until more data comes in.
The reality seems to be that if you're not seriously ill after 7-10 days, it's unlikely you're going to end up on the critical list - never mind dead.
But cases aren't being marked resolved for 2-3 weeks, just in case.
I'm not saying the CFR will go up in South Korea. I'm saying it's still early days to make the claim that it will definitely stay at 0.7%. When we get from 97% of cases being unresolved to something like 85% of cases being unresolved, and the CFR is holding steading, I'll be much more ready to spike the football and celebrate the intervention.
None of which is to say we shouldn't be copying the South Korean playbook closely. They've done a damn-near miraculous job of keeping the number of cases from exploding, and the preliminary CFR does look good. Even if it goes up, it still seems likely that they will have a lower CFR that many other places with a sizable outbreak.
Their response is the bright-spot so far, and we should absolutely be copying their playbook. I'm just saying, it's a little early to tell whether their playbooks is excellent or just really good.
Fever and a cough (usually dry) are the most common symptoms.