The weakness of a telelever is the weight of the frame to support it, lack of steering feel, complexity in both design and manufacture.
To calculate the variable angle you need 2 sides of a triangle and a included angle. We have one side of the triangle which is the wheelbase. Next we need the distance from centre of rear axle to the steering pivot on the top clamp. This is not known to anybody but the designers. The included angle can be measured or calculated if we have the height of the steering pivot from ground. Another measurement that is not known to the public. The 3rd side will vary and represents the front suspension. So how do you want to calculate this movement or are you hoping to be part of the design team? The fact is that on a telelever system the front axle moves through an arc (the animation is not very clear) and telescopic forks move in a linear way. Not easy to make a mock-up of the telelever that can be used to demonstrate the arc.
So once again the angle of movement is really not relevant to the discussion here. So instead of posting on here demanding somebody does the thinking for you, just pick up the phone to the mothership and demand an answer. Surely that would satisfy your search for enlightenment.
I thought one of the advantages of Telelever is that, unlike telescopic forks, you don't need a very strong steering head at a high location to take all the front suspension loads, so the bike frame can actually be smaller/lighter with the main load bearing attachment being lower down at the front of the engine.
Not sure that the lack of steering feel is an established fact, and opinions seem to go both ways on this, but the slight give in the joint links which connect the stanchions to the yoke may be a factor in this, and I grant you that even if not really much more complex, it does have more parts to find space for than a telescopic fork, and pretty much precludes a single central radiator, so makes the cooling system more complex too.
Regarding the working out of the change in angle of the stanchions which we have been debating, and which may have a bearing on the crimp loosening problem, I think it is a bit simpler than you describe. The angle we are after is the one between the brown coloured link in the diagram below, and the adjacent black coloured link. These two together with the blue coloured link make up a triangle.
In this diagram we need to know the length of the bottom wishbone/link coloured blue, which is the distance from the axis of its pivots to the point where the lower fork sliders attach, effectively the centre of the ball joint. I will choose the names for these distances to correspond with the online calculator I have found for doing the required calculations, so let's call this distance c.
We then need to know the vertical distance between the link pivot axis and a line going though the centre of the two joint links in the yoke to which the stanchions attach - let's call this distance a.
Both of these two are fixed and should be reasonably easy to measure.
We then need to measure the length of the brown coloured part which is the vertical distance between the attachment point of the lower fork sliders to the wishbone and the stanchion attachment point to the yoke, effectively the centre of the joint link. This has a maximum and a minimum value and we need both to calculate the maximum and minimum angle of the stanchions, and hence the range of angular movement the stanchion is forced to move through.
The maximum is easy - just support the bike so that the front wheel is off the ground, and measure the stanchion from the centre of the joint link which attaches it to the yoke, to a distance down from the yoke which corresponds to the wishbone attachment level, effectively the centre of the ball joint. This point on the stanchion may be inside the lower slider but its distance inside should be possible to determine by inspection - let's call this distance b1.
The minimum is more difficult as it would not be practical to fully compress the suspension. However if we believe BMW's published figure for maximum suspension travel then we can simply subtract this from the measured value b1 - so let's call this minimum figure distance b2.
We can then use well established methods to calculate all the angles of the triangle, firstly using distances a, b1, and c and then again using distances a, b2, and c. We can then compare the two angles between the brown and black sides for both calculations and see how much it changes between minimum and maximum suspension compression. This angle is designated angle C in the following calculator.
This online calculator will do the job for us:
https://www.triangle-calculator.com/?what=sss
For more theory on this see:
https://www.mathsisfun.com/algebra/trig-solving-sss-triangles.html
