Hi Mauro,
As roberto says printing direct from firefox for OS/2 is almost impossible. Because of that I have installed an Apple Color Laserwriter to use when printing to file as a PDF.
Regarding printer ports. As I said before I am using PSCRIPT.DRV with the PPDs for both my Brother printers added. To add the SLPR port use the
'Install New Port' button on the 'Output Port' page. Then open the SLPR port propertied and fill in as necessary (mine shows what I have for the postscript printer with PCL I'm not sure).
Since your printer has postscript embedded I would recommend that you use it that way even if it does require you to clean up the PPD and add it to the driver (see the readme included with Alex Taylor's PSPRINT driver for how to do it).
Thanks both Roberto and Ivan, good advice for me that I was testing printer output with the wrong application, I think that it will be better doing on the OS2 advanced editor, which has a printing menu.
Then I tried to apply Ivan suggestions, but below you see what is the result, and here I stop again :
https://ibb.co/hp02yAdo you think it would be better restarting from an empty printer manager (no printers - no drivers) ? Or should I be more radical, restarting from the saved system image just before all printing software installation consisting in PManager, IP Spool, Cups ?