Karl Popper had said that as a good comparison: The developments of scientific methods are like a casting a net on natural realities. The intervals of net become narrower by time. In my opinion the intervals of net are large yet in analysis of SR. We have to acquire more precision.
Your successful figure supports my theory and it menaces the theory of SR; because SR needs isolation from natural reality. For example the theory uses single line and direction.
If we set again, the Lorentz's analysis step by step on your figure, the defects of SR will appear with clarity.
If the points "So" and "Dı" are marked on the light coordinate system, the distance "SoDı" is the reel amount of the light's road; because the light started to travel from the point "So" at the moment of "To" and arrived to the point "Dı" of detector at the moment of "Tı". I fixed exactly/absolutely the point "So" due to "light coordinate system". Henceforth the theory of SR never says "The light travels by the value "c" of velocity too in relative system which it has motion".
Let's go on: In the theory of SR the source is constrained to travel toward the same line and direction in the train example. This necessity may pass over due to your figure. To fix the light's velocity for the distance "SıDı" and for the time "t = Tı -To" gives a different absurd relation by Lorentz's procedure. The special isolation protects the theory or it is the reason of illusion (In fact this isolation obtain that the existing of flash impulse has singularity. But the reel form of events as your figure the flash impulse appears at two points (Dı and Fı)
To establish an absolute coordinate system (imaginary) and marking The point "So, Sı, Do, Dı, etc" on this system solve this illusion or confusion.
The original text of SR needs to establish a new point "Fı" for light (flash impulse) and the light passes the distance "SıFı" by the value "c" of velocity for the time "t = Tı - To" and SıFı = c.t.
If the observer or a detector is in operation together the source and the light, the results of SR are under menace.