Older HP Color LaserJet is only printing Gray

I have a nearly 20 years old HP Color LaserJet 4700 dn printer. It works great under Linux, creating color prints that would require a very expensive printer to match. I'm trying to get it working under OSX Sonoma 14.3.1 running on a Macbook Air M1. I have a newer M2 too, but I need to get it working on this one first.

Bonjour detects it and sets it up on port 9100. The problem is that it is only printing rather low resolution grayscale. It seems to have something to do with the driver. I have tried several different configurations, one is to use a PCL 4/5 driver. That doesn't even give me the option of color printing. I have also tried a generic PostScript driver, which does allow me to use a printer based color model or ColorSync, where I have tried both Automatic and a CMYK model (which works great under Linux). It just prints a page with an error:

ERROR: limitcheck
OFFENDING COMMAND: image

I have also CUPS running on a Linux box, which the macbook discovered, I have tried going through that too, to no avail. It may be a path to go, though, if I fail to set it up directly on the mac.

I've been looking further into CUPS to see if I could get it working there. I see in /private/etc/cups/ppd/ where I find some PPDs that appears to have been created by the printer setup tool. In there, I find that the printer has been set up with

ColorDevice: False
DefaultColorSpace: Gray

I've tried simply changing that to True and RGB. Didn't work.

There are PPDs for Linux for this printer, so I tried copying that into the above directory in the hope something would pick it up, but that was a bit optimistic. I don't know a lot about OSX...

Funnily, it detects that the printer has color cartridges, but not that it is a color printer.

Any ideas on how I can get color prints for the macs?