Forgive me, but just to clarify:
In this review Caeruleum states that the Platinum Cool M and F nibbed pens reviewed write with a line width more congruent with European M and F sizing,
Enewton's experience was stated to have a Platinum Cool M write more like a European Fine.
And while my Platinum Preppy Fine 03 writes more like a European Fine, I must ask for clarification: How do the nib sizes on the Platinum Cool run? Are they more typical of Japanese sizing or do they run similar to average European sizing (as is stated in the review)?
Did sizing possibly change? Is it a natural variation?
I can't answer whether sizing may have changed or how much natural variation there is since I only had to samples and don't think that is enough to make a valid observation I could generalise. Thus I would recommend Goulet's Nib Nook where you can choose from images of many many writing samples and for example compare a fine Platinum Cool to a fine and medium Pilot Metropolitans and a fine Lamy steel nib which is what I just did. To me the Platinum looks closer to a western size given we consider a Lamy steel nib representative.
There also is a video by Brian Goulet writing with a fine and medium Cool and a gold-nibbed fine Platinum Kanazawa Leaf. Here he says the Cool runs finer than a western counterpart. He writes on 5mm ruling, so you you can use this as an objective standard and compare it to the pens you have by writing on 5mm (Rhodia).
Stephen Brown made a review writing with a medium Cool here. Maybe this helps as well.