I believe complaining is the weakest form of criticism and offers no benefit to anyone truthfully. I think there is a better way to format your "constructive" criticisms in a manner that won't offend those that differ from your opinion; that is the difference between a true critic and basically a whiner. Is complaining even an acceptable action in reality?
From what I gather complainers/whiners are usually regarded as children and ignored unless they plan to do something about the situation.
In truth do anyone's critiques here really hold any value or benefit anyone but the naysayers themselves? Highly doubtful. Kalafina is a professional group and I'm positive they dissect their performances themselves and know what needs to be improved upon.
If we look at the performance of sprinter, it's the 20th song they performed; therefore, I'm pretty sure fatigue and mild exhaustion is a contributable source to the occasional mistakes they made. Obviously it won't sound the same without Maaya, but basically its beating a dead horse to constantly bring up her departure. Maaya is gone and honestly they never needed her in the first place. Four is a terrible number to have in a vocal group so I think it's for the best she is gone. Also the only song she ever had any impact in was sprinter because she is basically indistinguishable from Hikaru in Aria. Additionally, they are HUMAN and they are capable of mistakes just like you, me, and the random guy across the street I mean what level of expectations are we setting for them in their concerts? Absolute perfection for every song with not a single flat note? Nothing wrong with having high standards but expecting them to be like Haku Mitsune without a single wrong note is foolish. Are we expecting studio level perfection like their albums and singles? Why? What is the point in having a concert without any flaws? Otherwise we could just listen to their albums and capture the same experience. My perspective on concerts is that you get to see them...the REAL them behind the studio magic, their capabilities as true singers, and their humanity. A live performance is raw and devoid of any touch ups a recording recieves which makes it an entirely different experience. Maybe certain critics are failing to make that distinguishment between the two and setting expectations that should be set for recordings and not live performances?
There is nothing wrong with disagreement because congruence in opinion would make this site dull; however, there are better ways to execute your opinion without offending others. Do it tastefully with supported arguments not with silly complaints.