Hi Ant,
I don’t have the Bambu Lab petg-cf filament but I do use other brands.
With PETG-CF keep your layer height @ min 0.20 with a .4 nozzle and with a .6 nozzle you can go to 0.18 layer height min and I run my petg-cf at 0.25 layer height if using a .4 nozzle.
With PLA-CF you can go down to 0.16 with a .4 nozzle.
The wall count you should do 3 or more with PETG-CF it helps for infill heat and stronger parts.
PETG-CF is happy up to 30 angle when you hit 45 angle it will start going downhill unless you have better cooling.
If you can mod your part so the rear wall overhang is 30 degrees it will come out way better
with petg-cf.
On the bottom holes you have two bridge overlapping so if you up the wall count it will change the bridge pattern. Also you can set your bridge speed to 30 mm/s and see if you get better results.
The box you are printing has some very small outer wall ledges and your retractions are being placed on these ledges so on this part you would want to paint the seams like the photos. Maybe you can even tune your retractions better.
You might try changing the cooling settings and see how your petg-cf works out and I will also change the slow printing down for layer cooling on or off depending on the part design.
As you also found out some filaments are better for the part design so sometimes you have to use a filament that will be the best one for the part design.
Have a good one 