If you’re worried about progress slowing down, it’s just that both of the main engineers on this have been working on some bigger architectural bits recently rather than minor fixes.
We know those things need to be fixed for release.
You’re not wrong, that’s the natural way things go because the old tool has had many years of fine tuning and the new tool is fresh code.
However for the same reasons there’s a lot of impacted legacy code which prevents you from improving things any further in the old code so you have to stomach a full or at least partial rewrite at some point of you want to be able to unlock more potential.
No matter how well you write a tool, circumstances change. The current Explorer was written back in 2012 for 100x less complex experiences. You can only take a given codebase so far.