How course is course? Anything more than orange peel suggests dirt/reaction/vapor pores. Many things can influence it at the application stage, ambient temperature, panel temperature, paint temperature, airline temperature, ambient air moisture, airline moisture, humidity, ventilation, ventilation flow direction, airbourne contaminants, airline contaminants ........ It's unlikely you have a booth where you can control these things but have a look at your setup and equipment and consider where the issue might be. Drying is another big area where issues can occur, too hot/cold, too quick, again with moisture. If you applied multiple coats did you allow time to "flash off", where you let the solvents evaporate from one coat before applying the next? This is where vapor pores can occur. Some machinery/synthetic/enamel paints need to be mixed and thinned within a certain temperature range in order for the chemical reaction of thinning the pigments and binders to happen properly (heat being the catalyst, you can sometimes get away with stirring like a maddo to generate some heat).
As for post application treatment, as has been suggested, maybe some areas have not gassed out completely yet. After doing the bonnet did you look at the surface of the polishing pad? Did you notice any clumps of paint? A cutting compound removes a micro layer of paint and this ends up on the pad, concentric behavior of the particles causes them to group together and bond to each other causing several clumps of paint which then harden as they are compressed and worked over the panel surface. If you then took this and moved it across a fresh panel it will scratch the paint surface as the lumps of paint on the pad are now harder than the paint on the panel. If this is the case, you can wash out the pad and carefully use a nail scrubbing brush to remove spent paint and product. Dry with an airline so as not to splatter the vehicle when you go back to compound it.
I appreciate you may have a fairly Heath Robbinson setup as most of us have to do mechanical and bodywork in the same shed, and I have rambled a bit more deeply in to the subject than you may be interested in, but hopefully there's something in there that helps you out