From your markup @Bry was correct about no red wire.
I modified your markup (because I don’t like crossed wired) and added a white in the right hand box.
This is what I came up with, please check it against your wiring, especially the wire I marked “G”
Note the slots on the current dimmer are not the key to the wiring, the colors are. In that type of dimmer the power must come into the black wire. The two red wires are actually interchangeable and go to the remote 3-Way switch.
Assuming you are adding an Inovelli Red or Black, You could simply replace the current Lutron Rotary Dimmer with the Inovelli.
To do that you would:
- Remove the Lutron.
- Connect wire A to the Inovelli “Line” screw
- Connect wire B to the Inovelli “Load” screw
- Connect wire C to the Inovelli “Traveler” screw
With 10 lights connected to the dimmer you should have little trouble operating the Inovelli without a neutral wire. Be sure the total LED wattage does not exceed the Inovelli specification.
However if you are in a exploratory mood and have access to a multimeter, we can see if the wire D is a neutral wire and use it on the Inovelli to make it less dependent on the load characteristics to operate.