Good evening, blizzard development team. I take the time to write this topic to comment on an error in the card mentioned in the title of this publication. Today after playing in standard the card repeatedly presented an error in its exchange mechanics. At first I thought it was a casual error, but to serve me keep trying the exchange. And as a result of this the error persisted at least 5 more times. Try to change the coin in the opponent’s hand, the hunter’s secrets, the druid’s aquatic form. The opponent did have them in hand and they were played in the subsequent turn. All these mentioned cards could not be exchanged with the mechanic of the barbarian sorceress. Which as a result was losing a key move in the game, therefore losing the game. Please review what I am commenting on since it is very fruitful and discourages you from continuing to play. Beforehand thank you very much. 
Do you have a recording of a game where this happened? If so, then please link to it.
The most likely explanation is that your opponent did indeed have a coin in hand, or those other cards you mentioned, but also another spell. And that other spell was picked as the random target for Barbaric Sorceress.
Another possible explanation is that you somehow summoned Barbaric Sorceress, but not by playing from hand. If you read the tooltip that appears when you hover over any card with Battlecry, you will see that these trigger only when a card is played from hand.
And yes, it is also possible that there was in fact a genuine bug. In that case, Blizzard will need to know as much as possible about the board state and the contents of both players’ hands, so they can try to find what caused this.
I believe the effect of that minion is to swap the cost of a spell in your opponent’s hand with a spell in your hand.
Did you have a spell in your hand?
Im currently in a game where this happened. I had rune of archmages in hand, next turn the priest played 3 spells, including the coin I gave him. I had 3 targets and barbaric sorceress didn’t choose a single one.
Are you sure the priest didn’t have another spell in hand with the same cost as your spell? Swapping identical costs would appear as no effect at all.
I had a similar problem but with my own cards, I only had 1 spell on my hand in multiple games, and used the sorcerer to exchange its value, it was big spells standard mage, but the value of the card didnt change, this happened in at least 3 games, 2 yesterday and 1 today, i thought it was a casual error too, but its getting more and more annoying as it continues to happen
It helps to post a link to the game on hsreplay or other similar site, if you played with an add-on that tracks and saves games.
Do note that many players have now learned to play around big spell mage, making sure to use their cheap spells as early as possible and leaving only expensive spells, or none at all. If your opponent has no spells, then Barbaric Sorceress will not do anything. If your opponent has a spell of the same cost as the one you are holding, and that spell gets randomly selected, then it will switch costs but obviously without visible effect.