I don't see any reason why you need a schematic. If you copy where the tracks go on the original board, your copy will work the same.
As others have mentioned, schematics are a way of understanding the function of a circuit. Often a schematic is drawn and a PCB is made from that. Sometimes a PCB is reverse-engineered to understand its function, and rearranging onto a schematic, with +ve at the top etc makes it much more understandable. It's good to do that for the Hall sensor board so that you know what components to use and how to fault find.
There are several things that the schematic won't tell you. You will need to get the overall board dimensions, the position of the Hall sensor, the position of the LED and the position and diameter of the hole correct. You seem to have done those things on your 3D CAD, and then all you need to do is join the tracks up like the original.
Your schematic has the base and collector swapped on the BC858, and the LEDs the wrong way round. Where you have the blue lines crossing on the layout, they shouldn't. The track from the BC858 that goes to R2 (and other components) is correct. The tracks to the BC858 from the LED and R3 should go to the nearest pins and not swap over.
You might be getting confused because the BC858, like nearly every SOT23 transistor, is not laid out in the package like the schematic symbol. The one pin on its own on the package is the collector. The one connection in the middle in the symbol is the base. It's (usually) shown in the data sheet:-
https://assets.nexperia.com/documents/data-sheet/BC856_BC857_BC858.pdf in the diagram on page 2.
Which all comes back to the fact that if you lay it out like the orginal, it will work. If you go via a schematic, there are lots of mistakes that can be made.