After testing out many different types of pens and line widths - the absolute widest I can use is 0.5mm, which is about a western Extra Fine, but I usually prefer 0.38 or 0.28 which ends up leaving me with my EDCs; my PCH912 PO Nib and the Preppy 02 EF.
You seem to have some fat pens or very absorbent (spreading) paper...
My currently inked "western" nib pens (vertical x horizontal - optical comparator, using metric scale [inch scale reads finer, the metric is marked at 0.2 increments, so I'm having to estimate the splits], on Levenger recycled 3x5 note cards)
Lamy Al-Star M 0.5x0.4
Sheaffer Stylist/Imperial (727/777?) B 0.7x0.6
Esterbrook 9556 "Firm Fine" 0.5x0.3
Esterbrook 2668 "Firm Medium" 0.6x0.5
and for giggles
Lamy Joy 1.1 italic 0.7x0.0.3
inked Japanese nibs:
Platinum President M 0.3x0.2
Pilot Falcon SB 0.8x0.4
Pilot Custom 912 FA (no pressure) 0.2x0.2 (pressure) 0.9x0.4
In my hands, Lamy Medium and Esterbrook Fine both meet your upper limit -- what you describe as an Extra Fine nib. Note that even the "1.1" italic only produced a 0.7mm line for me.