Dear Salvo,
I think Forte Polygrade is more of a cooltone paper. Cooltone papers tent not give the typical yellow colour. You might try a warmer paper. I use cooltone combined with gold toner for a cold look, colour turns toward blue.
The money spend on Tim Rudmans book is very well spend.
If contrast is too high usually exposure was too short, expose for colour - develop for blacks, as Tim said in his book. I usually take the normal printing time and mulitply by eight (= 3 stops). When the developer gets older I sometimes just expose 200 or 300 secs at 2.8 for a 12*16'' print, which would take 30-45 secs at 5.6 as a regular print.
Some developers or papers work better at higher temps like 30°C, e.g. Agfa at that temp gives a rather look, you will not get at 20°C.
If developing times are too short use a higher dilution AND add some old brown, which is how used lith developer is called.
Personally I use Champion Novalith (Made in UK) 50 ml A and 50 ml B to 1 litre, or 2 fl. oz. A plus 2 fl. oz. B to 2 pints. I mix this 3 hours before printing and just let it age in the tray.
Health risk statement: Lith printing can be addictive!
Kindest regards,
Wolfram