That is irrelevant. The map is not the territory. They are two countries in reality; that is, they operate as two separate sovereign countries in every practical way, regardless of what legal fictions are maintained for political reasons.
This atlas is presumably supposed to be about reality, not about legal fictions.
(BTW: North Korea and South Korea officially claimed to be one country until very recently, and South Korea still does. But every map in the outside world shows them as two. Why should China and Taiwan be treated differently?)
It only looks like this from the West, where the support for independent Taiwan is much higher than in Taiwan itself (not to speak of PRC where it's non-existent.) People in Taiwan don't perceive China as a different country (the way that French perceive Germany for example) but rather as a different (unfortunate) regime over the same nation.
> This atlas is presumably supposed to be about reality, not about legal fictions.
With the current reality in east Ukraine/Georgia/Northern Cyprus/Israel-Palestine/Kosovo/etc.etc.etc., I'm not sure if it's ever possible to get a map that will satisfy everybody, as what is "legal fiction" to you might be "internationally recognised borders" for someone else.
I think this misses the point. It doesn't matter if 0% or 50% or 100% of people in Taiwan or anywhere else believe that Taiwan is legitimately independent. That has no bearing on whether it actually is, in practice.
An "Atlas of World History" should strive to portray who actually controls territory in the real world, regardless of whether that control is "recognized" or "legitimate". Otherwise it is an "Atlas of Political Thought" or "Atlas of International Law" or something else.
> With the current reality in east Ukraine/Georgia/Northern Cyprus/Israel-Palestine/Kosovo/etc.etc.etc.,
Yes exactly. For the same reasons, Crimea and various parts of East Ukraine should be labeled as part of Russia, East Jerusalem and places like Ari'el should be labeled as part of Israel, etc. This has nothing to do with whether I think any of those borders would be "legitimate" or "legal" or what percentage of the people who live there accept them.
You may say that ROC is a de facto separate country, although the constitution doesn't imply necessarily so, but simply that there's a different government.
The fact that the international community and even it's own constitution doesn't recognize it as an independent country shows that it's more than legal fiction and simply that de facto China is still under civil war.