Well, suppose the objective is to have only one control toggle (or whatever you want to call it) that selects between CA and CC. Here's one method:
This applies a so-called Exclusive-OR or XOR gate which is about 10 cents per gate in small quantity. These are 5V logic IC's so obviously we are restricted to 5V operation - here's the 74AC86 from DigiKey that has 24 mA of high or low level drive (74AC family has symmetrical capability) so it can directly drive a pair of signals. I'm figuring each LED will be plenty bright at, say, 5 mA or so.
They come 4 gates per 14-pin DIP so you'd need 2 for this application. I show a SMT version which might be a good way to start messing with SMT devices. They also come in regular thru-hole DIP.
The diodes on the left are as-is from existing circuit. There is a single 3-pin "jumper" as before shown on the bottom.
When in the CC mode (pins 2-3 connected), GND is applied to each XOR gate. This makes the gate a NON-INVERTING buffer so the outputs drive a CC LED head. The common resistor is also tied to pin 2 of the jumper so this means the LED common returns to GND as it should be for CC.
When in the CA mode (pins 1-2 connected), 5V is applied to each XOR gate. This makes the gate an INVERTING buffer so the outputs drive a CA LED head. The common resistor is also tied to pin 2 of the jumper so the LED common returns to 5V as it should for CA.
I show this simply in the spirit of discussion. That is, you can't beat the price of an NPN transistor for a penny or two. This method would cost maybe 75 cents more per board in parts. It does have the advantage that all the parts can be soldered down and the polarity can be changed with just one jumper. But it can only operate on 5V DC and cannot drive the 100+ mA per LED output of the NPN method.