I can definitely see where some of the confusion is coming from. If we naively believe what the chief liar Christ Roberts has been telling us for the past three years then CIG has turned the CryEngine inside out and outside in. It is supposed to be so heavily modified as to be unrecognizable by now.
The other puzzling bit is that CIG has supposedly been working on a total netcode revamp for about three years as well. Netcode has pretty much become their standard excuse for when shit doesn't work (i.e. all the time).
So, it is indeed quite mysterious how they can simply switch to Lumberyard with a heavily modified CryEngine or how they can simply (un)plug their 3+ years in development netcode to make it work with AWS/Lumberyard infrastructure.
Something is not right here... they either lied about the level of modifications they made to the CE or they lied about their netcode revamp or both.
You can not simply roll back from heavily customized to standard CryEngine/Lumberyard overnight.
It would be a biblical miracle if this switch did not require an adaptation of the dev tools, the (net)code base, the interfaces, the plugins, the scripts, and all the other customized elements etc. etc.
I don't get how this, according to CR, "... took us a day or so of two engineers on the engine team". That does not seem possible to me unless they totally lied about their own previous work on the CryEngine. Or his definition of the "core of the engine" means they replaced the "copyright by Crytek" by "copyright by Lumberyard" (2.6 splash screen shows no references to Crytek anymore).
What he is not telling us, of course, is that the "non-core" of the engine (and their own tools) is probably going to require a massive rewrite and revamp in order to make the adaptations.
On a whole, I still consider this as their admission that they could not hack the netcode. 3+ years of netcode revamp right down the toilet to be replaced by AWS infrastructure. Good job. Not.