The co-ordinates for the temple that got deleted are X=503, Y=121, Z=-1816.
I hope this works, let me know if it doesn't.
https://1drv.ms/u/s!AmggMJ2_r8K3hO0nxWqj_5KXtHAg0A?e=71HL7Y
She has over 340 GB free on her hard drive so I doubt that that's the cause of the issue.
It looks as though ancient cities are generating through buildings, ripping out huge portions, then removing the structure afterwards.
I mean there isn't anything to report. We gave up with the world when that happened for fear it would happen again. This issue has never happened again after this one time.
Although, my friend's hard drive ended up breaking and needing to be replaced about a month after this occurred and I suspect that that was related to this issue rather than it being a bug within Minecraft itself.