Yes, it conclusively proves tunnels were dug using globe earth calculations and measurements to avoid obstacles. And they successfully avoided the obstacles by doing so. That's it.
No it doesn't.
It proves tunnels were dug. End of story.
Sure it does. Massive engineering/construction projects like something of the magnitude of Crossrail needs 100's if not more extremely detailed plans for every aspect. From boring, to cementing the tubes, to running the electrical and HVAC infrastructure to stations needs, to you name it. You can't deny that detailed plans are required.
And all of those plans reference the London Grid Survey measurements & calculations. All plans were predicated on the WGS-84 data and a globe projection provided by the survey. Period.
Without any evidence, all you are saying is that the plans are fake and all involved from Engineering all the way through to Construction are lying. If you want to rely solely on your sense of "logic" and faith in your theory, all of it faked and all of them lying is logically implausible.
Crossrail isn't the only example. For example, even the Chunnel project had to be re-surveyed because England and France relied on two different globe projections. So the RTM87 grid was created, unifying the effort using a singular Transverse Mercator globe projection. I guess they are all lying too and somehow got it right even though they were wrong.