Thanks, we're familiar with the quirks of EN 166.
And that's not EN 166.
My Brave-fu isn't finding a "liberated" copy of EN 1731 F, so I have no idea what test projectiles or energies it claims to stop. However, I can find forestry helmets with fine mesh that claims to meet EN 1731 F, and I wouldn't trust that for airsoft use.
It's reassuring that you have tested yours, but 2J of 0.2g isn't the same as 2J of 0.46g. Don't get me wrong, I use mesh myself, and DIY at that, using 3.5mm hole / 4.5mm pitch 1mm thick stainless hex. I'd be interested to hear how that (literally) measures up to the Nuprols.