You're right. The alphabetical order follows the time progression of the mutation.
That was how the different variants of the virus were named in one of the earlier studies of the virus genome. Each of the variants (A, B, C ...) actually represents a group of the virus subvariants which is only different from each other by one to a few mutations.
This way, variant A in China maybe just one or two mutations away from let's say the variant A in Australia.
I think there is one idea that is not particularly well publicized, whether the virus had weakly established itself in a place like Central Asia/Middle East which doesn’t have huge population densities and not always well developed. Since the travel traffic is not huge, it can account for the sporadic early virus detected in Europe.
Since the populations are not huge, you don’t see the same kind of mass deaths and the older population is smaller (due to lower life expectancy).
It could also explain how the virus wasn’t spreading rampantly in March 2019 in Spain or Italy or whenever they say it was detected in sewage samples.
We know the lack of mass deaths in China outside Wuhan and low infection rates in overseas Chinese communities means the spread was pretty contained. Similarly, we should apply that same logic to Europe (unlikely to be strongly in the wild there in 2019).
Although I am loathe to say it, but the western media is right to call out the Chinese media for trying to pin it on Europe. Two wrongs do not make a right. Part of the reason it is such a mess is because people seem to no longer follow the facts.