So Apple's TB3 adapter is only for data... only real use I found is when using the old computer in Target Disk Mode to transfer all data to the new computer. (Time Machine is not very good at computer migration)
I have the exact same problem and after much search, came to this solution:
- Dual-Link DIV to DisplayPort using Apple's connector
- DisplayPort to USB-C using this connector Which is a USB-C to Mini-DisplayPort and Charging Port Adapter {Amazon.com}
Keep in mind that the Cinema display also needs a USB-A connection (I'm guessing to provide power to some internal circuit for link negotiation?), so you'll need a separate adapter from USB-C to USB-A.
I'm also an amateur photographer and shoots with a Canon 5DsR, editing my photos using an AdobeRGB LG 4K display (10-bit color to support AdobeRGB). I've also tested the DisplayPort adapter on this display and it works flawlessly.
On a side note - reason why you'll need a separate adapter for USB-A instead of having the USB-A built-in to the DisplayPort adapter is that only way for USB-C to support DisplayPort data-rate is using Display Protocol, which turns a bi-directional USB connection (10Gbit/direction) to a uni-directional output port (20Gbit total). If you work out the math: 3840 * 2160 * 10-bit color per channel * 3 color channels (RGB) * 60 Hz = 15Gbit/s.