This kind of ill-bearing attitude is rather detrimental when one is trying to comprehend and engage with historical practice for numberless reasons. Presumably, they did not thought them innocent, but if sentenced, rather guilty. A legion of late medieval and early modern laws are deemed illegal and unethical by contemporary standards and laws, but that is not the issue at hand. Therefore, presumably, outside of a few peculiar occurrences, where one can imagine the accuser feeling shame for some other reasons, they did not feel shame, on the grounds that the accused was not innocent to them. Although I am much more familiar with a broadly Continental setting, and to a degree British, I can still offer a few words.
Times when the water trial, or "swim a witch" was used, is greatly exaggerated in popular discourse. In Europe, this kind of practice was officially forbidden in some states, though the lack of oversight and centralization made this prohibition notably ineffective, so the cases in manorial and city courts still sometimes used it. But not at all at the scales sometimes imagined, but to say anything more substantial here, we need to be specific about time and place.
In America, this went even further. Prior to Salem trials ( perhaps /u/dhowlett1692 can add specifically to Salem trials ), roughly from mid-seventeenth century, among 90 recorded cases ( there probably were more ), amongst the known verdicts, only in two cases was the trial by water used, and in both cases, the accused escaped the colony. ^(1) In America, we get two influential treaties on the subject, William Perkins's Discourse on the Damned Art of Witchcraft and Richard Bernard's Guide to Grand-Jury Men, published respectfully in 1608 and 1627, both of which denounced such practices, deeming them unbiblical and unscientific, and went even further in calling them a "popish error". Even if the event took place, like two examples from Connecticut, Elizabeth Clawson and Mercy Disborough, both of the accused requested the test by water, and both did not sink, but the court that presided the trial would not take the ordeal seriously. The jury was unable to reach a verdict, so the case went to the General court. After the opinion of ministers was drafted, one point of it read " with the generality of divines that the Endeavour of conviction of witchcraft by Swimming [was] unLawfull and Sinfull. " The ministers likewise did not pass a verdict, but heavily questioned all evidence obtained. Though the jury afterwards did in fact, even with the opinion of ministers at hand, sentenced Disborough to death, but a petition to General courts after this development got a response that the second half of the trial to be illegal, and was thus shorty after acquitted.^(2)
1 Drake, F. (1968). Witchcraft in the American Colonies, 1647-62. American Quarterly, 20(4), 694-725.
2 Godbeer, R. ( 1992 ). The Devil's Dominion: Magic and Religion in Early New England.