Using the AnyCubic slicer as the last time I checked I couldn't really use anything else due to no profiles, that was a while ago though, I might try Orca again and see if it has anything useful filament profile wise.
What sort of speeds are you using, the stock PETG profile I am using as a base has 12mm/s flow rate cap, but might drop that down a bit and see if things improve, temp tower is looking like 245 is where it likes to be, I'll do flow and PA tests later, was just looking for those that had used PETG-CF before and had a bit more of an insight as to what is different between that and normal PETG as that's the profile I'm using as a base..