There's little point in re-certifying, because if the pens only contain 80% of the dose in these conditions, they will almost certainly fail the certification in those conditions. They presumably contain the dose they do to ensure that device is as safe as possible - so that it's high enough that it can save the patient in almost every case but low enough to not cause other issues or side-effects.
What that third-party test shows is that if all you have available is a supposedly 4-year past-expiry pen and it's been kept at all the wrong temperatures, you should probably still use it in an emergency because there's a good chance it will still work. Not a big enough chance that they recommend using expired pens, but enough that if the choice is probably dying or using it, you absolutely should use it.
