The first time I tried JLCPCB assembly PCBA, I also had components placed at crazy locations on the review.
The second time it was much better: all components placed at their correct locations with only the orientation that is sometimes wrong.
What I did this time is add an 'auxilary axis origin' in PcbNew.
You can place one easily in PcbNew: the icon to place one is on the right icon list, just after 'delete items' icon and before 'set origin point' icon.
You can place it for example at the top left or bottom left of the PCB (it does not have to be precise, it is just a reference).
You will have to regenerate the gerbers, drill and pos files afterwards.
And don't bother too much about component orientation as JLCPCB does manual inspection to check and fix thid specific problem.
But if you have OCD (like me
) you can modify the Rotation column value of such components and redo the supmission again until the results are good.
To be honnest I'd let them fix that part now that I know better how it works on their side.