Two thoughts (and I make them knowing fully why your hierarch does this - I've heard him do it myself):
1. The hierarch in question doesn't like it when people who can't speak a foreign language do it anyway; if you can't do Greek, then don't. The Liturgy isn't a means of practice, and it certainly isn't Language Lab for the celebrants; and it cannot be gibberish to those listening - if you're trying to speak Greek, do it well, just as if you're trying to speak English, do it well also. If I spork Angles nat tu wel, then in the context of Liturgy it trivializes the service to a point.
2. Correcting on the spot, while in bad taste and not very helpful to those who are making the mistakes (btw: I'm against correcting on the spot - I'd rather wait for a quiet moment to do it), it does actually clarify what the word is supposed to be for those listening intently. Remember, books are a recent addition (and I don't think they are as much an aid as a distraction), and additionally, we are a Faith that has fought over one letter in a word before (Homoousios versus Homoiousios) - proper pronunciation and speech is critical to staying out of heresy.
I'm coming very late to the party to say that I agree with this.
I have been corrected numerous times, usually after the service or quietly in the altar. I suppose some mistakes require immediate correction for the sake of the faithful or of preventing sure and certain disruption to the service if it is allowed to continue. I always welcome the correction because my faith is grounded in the liturgies of the Church in many ways, and I have known, from time to time, what it is to have my prayer and worship disrupted by clergy/servers/readers/choir, innovating, bumbling, or generally taking a slipshod approach to the worship of God. It can cause frustration, which is most unhealthy as we approach the throne of God in worship, and it is sometimes difficult to return to the place of humility and awe that should be our mindset in the Liturgy.
In taking part in the liturgical offering to God, I want to give the best that I can and I certainly do not want to cause a similar temptation to others. I fail but then I try again. I would think that all of us would have that attitude. Therefore, if I'm doing something incorrectly, I want to know about it so I can improve myself. So yes, I am grateful for correction, and I usually thank people when they offer it, (or engage in discussion with them afterwards if it's something on which I know there is legitimate variation or when I wish for them to clarify so I can understand my mistake). I certainly don't want to be "that slovenly subdeacon who keeps messing things up", to the point where I'm more of a hindrance than a help, and clergy try to find some reason not to invite me to serve without hurting my feelings if I visit their churches on special occasions.
So while I agree that very public correction is perhaps not the best way to go about things, (unless absolutely necessary), and that a bishop who habitually does this perhaps needs to re-examine the necessity of it and take into consideration the embarrassment and unnecessary hurt that this can cause, I also think that those who are corrected in this way should also practise some humble introspection.
St Barsanuphius the Great:
'When anyone is disturbed or saddened under the pretext of a good and soul-profiting matter, and is angered against his neighbour, it is evident that this is not according to God: for everything that is of God is peaceful and useful and leads a man to humility and to judging himself.
Instead of arching my back and taking offence because a bishop/priest/layperson has become frustrated with my mistakes and corrected me, I should remember that such frustration does not exist in a vacuum but that it is a response to my
mistakes - something I
have done. While the person doing the correcting may be wrong to get frustrated and may be wrong to humiliate me by correcting me in such a loud and public way, the fact remains that the temptation for him to do this would not be there at all if I would just do things properly in the first place. How can we lay temptations before people and then condemn them when they fall? Even if we ourselves don't consider the matter to be of any great significance, and don't mind whether it is done one way or another, surely we should still try to do it well if only for the sake of avoiding causing our brother to stumble.
Whatever it is, just do it properly. If you don't know how, ask somebody to teach you. If you know how but can't do it well, ask for guidace or get somebody to help you practise. We are brothers and sisters - we help each other and grow together. Then we come together and offer the best we have to God. And if we make a mistake, which happens sometimes, then we simply ask forgiveness and try again, because what I find as somebody who, (for various personal reasons) has had "doing it well", "getting it right" drilled into me from childhood as the way to approach anything, is that this is not a legalistic perfectionism. What bothers me is not when people are trying to do it well and make a mistake, but rather when they do it incorrectly, make mistakes, and seem not to be bothered, making no effort at correction or improvement, and then react with pride when people try to offer help. I am not a very good Christian in many ways, but it seems to me that this is not how we should come before our Maker in worship.
the liturgically-inept-but-trying-his-hardest Subdeacon Michael