IG can be augmented by other means, such as commissars.. but those are null points as you can apply buffs even outside of the unit itself, you don't add additional points to the base because it can be buffed, you apply those points to the item giving the buff. Base vs base 90points of IG vs 90 CWE Guardians. Math hammer/play test it out, the upgrade in stat-line is need to balance it out.
There's no need to test it because the rules are going to be changing. What is true, however, is that Eldar Guardians had the same WS and BS as Guardsmen across numerous editions, and I never once found that this was a problem. In addition, comparing units across armies in this way has always been something of a false comparison. In this case the comparison is problematic because Guardians are a support unit, except for Ulthwé, while Imperial Guardsmen are the primary forces of the Imperial Guard.
There has never been an issue with the balance between the two units because of cost or statistics. The problem arose in third edition when the range of the Shuriken Catapult was cut. That was the main problem for Guardians and that was, eventually, fixed.
Where does it state their training regime? Once a month every fortnight, once a year. Do they train as often as Aspect warriors, well no . The fluff does tell us that even while on the warrior path they "...deliberately continues to pursue the arts of peace..." it goes on into more detail describing the various peace fields. Perhaps the time ratio of warrior vs peace is inverted in civilian life.
I prefer to examine what the narrative actually says, rather than what it does not say. It makes it abundantly clear that Guardians pursue civilian roles when not on the battlefield. This is in complete contrast to Aspect Warriors. Civilians should not have superior WS and BS to professional soldiers.
It is not a great leap to think the Eldar would not loose their skills as quickly as humans do, if you accept that, then it is also not a great leap, that they would require less time to be spent on maintaining that skill set.
This is all speculation. Speculative narrative cannot be used to justify in-game statistics, otherwise we'd have all sorts of crazy stat lines and a mass of balance issues.
So what is the difference between a Professional (rank and file) soldier's ability to aim vs a trained Civilian? I would be surprised if there was a statistically relevant difference.
There have been so many debates about this in the past. You're welcome to search through them all. Start with the Eldar wishlisting thread and the Eldar redux topics. A brief summary, however, is that a professional soldier is always going to be more skilled and more accurate than a trained civilian. A trained civilian is not able to match the professional skills or military discipline of someone who is in the military for a living and for their career. Applying this argument to the Guardians versus Guardsmen debate and considering that Guardians would still have parity with Guardsmen should the WS and BS boosts be reversed, and it's evident that Guardians remain superior, as no other civilian force in the 40K universe would achieve parity.
What is 'super human'? Does Super Human mean Superman or merely better than human?
Does it really matter in this context? As Eldar Guardians are not described as being superhuman, I don't see how it's relevant.
You are a dying race, living in a galaxy constantly at war, you know your civilians are going to be used in battles, how much training do you give them?
You are living in a galaxy constantly at war, you know that at some point in your life you are going to have to fight, how often do you train?
As the narrative says, they are civilians. Their primary role is to keep their craftworld functioning as a living space. The Guardians are only called upon in times of need. For any small scale missions, most craftworlds are unlikely to send any Guardians into the fight at all. How much training they receive is not explicitly stated, but the fact that they are civilians is, and that is the crucial point.
Guardians can pilot vehicles (much easier to do when there is such advanced technology to assist in piloting any vehicle), wield a Shuriken Catapult (a very basic weapon in terms of Eldar technology), and use basic close combat weapons. That's about it. That's pretty darn good for being a civilian. Matching trained Guardsmen is just way too good and that's why the change needs to be made in the forthcoming edition.
It all really boils down to how you interpret the fluff, for me there is supporting material for it.
Having debated this point on and off since 2008, nobody has ever found any evidence in the narrative to support the argument that Guardians should have superior WS and BS to Guardsmen and to have parity with Aspect Warriors and Space Marines. There is no material to support that argument and I very much doubt that there ever will be.