The cut sizes are easy enough to measure area, even rounding down on each of them it isn't a high tech thing to calculate.
Originally (not long ago, one of the earlier stickies on safety) there was an alternate blowout plug spec, which comes out to an area different from the slot spec. It was something like a plug size should be 5/8" or 16mm, which leads to a plug surface area of 200 square mm, while the new slot-only approach appears to require 600 square mm of venting (3 slots, each 200 square mm). I remember it because the reference to the plug was in the body of the sticky, in plain text, while the "Better have 3 slots" was in bold green text at the bottom. That's when I said the notcigs delrin bottom cap already exceeds that spec, larger total area and there's no way it could be magically sealed since batteries get changed via it.
If the plug spec would have provided enough area for venting, then each of 3 slots would only need to be about 70 square mm, 2mm x 35mm, nowhere near 4x50. If you wanted even a 50% increase compared to the plug, you're looking at 3 x 35 or 2x50mm slots, not 4 x 50?
The spec does say "about", which implies it isn't as if some ultra precise measurement to verify the slot size, so I'm surprised that a photo showing the unit, perhaps with a ruler next to it, doesn't suffice. If you have to send one in, does it have to go to ECF home in the UK, or are the US contingent going to be stuck verifying venting?