To your first point, "The decision seems to be primarily a software architecture one...", this project has had involvement of the whole engineering team since the beginning. The whole org is on board with this change. It's definitely not happening in a silo.
> This is definitely the second system effect. It's going to take years to make this thing reliable and sunset the old product.
I hope not, but obviously we're not done yet, so I can't say how long it will end up taking to completely decommission the Python 2 app. What I can say is this: there are aspects to this project that are _simplifying_ our system and, for what's left moving from Python to Go, our intention is to port the business logic as close to a straight up port as we can get.
> - They're porting over the logic? Even if this is actually the right move, wouldn't a clean-room implementation potentially give better outcomes?
_That's_ second system effect, to me. We can't change everything and fix every problem now, so we're focusing on the changes that will help us move from Python to Go faster.
> - Why are they continuing to use App Engine if the writing's on the wall for 2024?
I don't think Google Cloud is disappearing in 2024, for one. Beyond that, again, we're not changing everything about our architecture. The way our data is stored is staying the same.