Do these VCDS traces explain my limp mode?

[VAG-Abound]

Turbo on our BKD has been dropping into limp mode pretty reliably on motorway trips for a few months. I've been underneath and dropped the turbo actuator from its mount so that I could wiggle the VNT lever around, and it seems to shift pretty easily. I've also put a hand vacuum pump on the actuator and watched the action from along the exhaust tunnel. It seems to run smoothly to the stop and back in the expected vacuum range. Also popped the vacuum manifold / distribution plate off and all the lines that I'd expect to do appear to hold a good vacuum.

I did a bit of VCDS logging and noticed that when the actual / specified on the boost control vary significantly from each other there is often a similar variance on the EGR control, such as in the areas I've marked with a red rectangle below. Is there likely to be a connection between these, such as vacuum system losing (negative) pressure? Could EGR action be dragging down turbo response and triggering limp mode?

BTW, the car went into limp mode towards the end of this trace. Looking at the traces I'm a bit surprised that the area in the first rectangle didn't do this as well. Is there a grace period of some kind before it will actually trip?

[Hmmm. I'm struggling to make image large enough to see easily. Top trace is boost pressure (blue=specified, red=actual) and lower is EGR (green / purple respectively).]

20190313a.jpg