The Sun article is second hand (1. the source likely heard those quotes first hand, and 2. the Sun reporter wrote it down). Baldwin's testimony was first hand. He met with Lincoln and reported what Lincoln said.
The Rev. Dr. Fuller, of the Baptist church, accompanied the party, by invitation, as chairman, and the conversation was conducted mainly between him and Mr. Lincoln, and was not heard entire by all the members of the Convention.
As the article said, "... a delegation from five of the Young Men's Christian Associations of Baltimore consisting of six members of each ..." That makes at least 30 people in the delegation plus maybe Rev. Fuller. It is quite possible with a group that large that some were far enough away or maybe in the hall that they couldn't hear well. They must have heard some of it, because the article said "was not heard entire ..."
... our informant could not follow the exact terms of the remark.
I note that you have misquoted the article. The article said, "our informant could not follow the exact turn of remark." Nor "terms" and not "the." Are you trying to illustrate how things change on repeated telling by different people, a la Russian Gossip or Chinese Whispers? I concur that that no doubt happened in some of the retelling of what was said by people who weren't there.
So in other words, "our informant" caught a few words here and there and pieced them together without much knowledge of the whole conversation.
Your comment is a stretch. The informant said where he couldn't hear or perhaps the conversation went too fast for the informant to follow. But the informant appears to have heard much of the discussion, or else he would say like he did, that he couldn't follow this part or that part.
Somehow over time, "And what is to become of the revenue?" got metamorphosed into "What about my tariff?"
The tariff quote might have its origin in Baldwin's Memoir as reported by Robert L Dabney in 1876 (based on an 1865 interview with Baldwin) and also reported his book, "Discussions with Robert L. Dabney, Volume 4." Here is an excerpt of the 1876 article and a confirmation of its substantial correctness by someone Baldwin told when he returned from Washington in April 1861. Lincoln's words below are shown in bold red font. [Source: see Link].
Lincoln seemed impressed by his solemnity, and asked a few questions: "But what am I to do meantime with those men at Montgomery? Am I to let them go on?" "Yes, sir," replied Colonel Baldwin, decisively, "until they can be peaceably brought back." "And open Charleston, &c., as ports of entry, with their ten per cent. tariff. What, then, would become of my tariff?" This last question he announced with such emphasis, as showed that in his view it decided the whole matter. He then indicated that the interview was at an end, and dismissed Colonel Baldwin, without promising anything more definite.
In order to confirm the accuracy of my own memory, I have submitted the above narrative to the Honorable A. H. H. Stuart, Colonel Baldwin's neighbor and political associate, and the only surviving member of the commission soon after sent from the Virginia Convention to Washington. In a letter to me, he says: "When Colonel Baldwin returned to Richmond, he reported to the four gentlemen above named, and to Mr. Samuel Price, of Greenbrier, the substance of his interview with Lincoln substantially as he stated it to you."
I quoted from the Memphis Daily Avalanche article as it was posted on line. If there's any distortion here, it was in the passage of the story from newspaper to newspaper, article to article, book to book, not anything I did. That was sort of my point: this purported quote became part of the folklore passing from mouth to mouth and pen to pen and being changed in the process.
Your comment is a stretch. The informant said where he couldn't hear or perhaps the conversation went too fast for the informant to follow. But the informant appears to have heard much of the discussion, or else he would say like he did, that he couldn't follow this part or that part.
You are assuming good will or trustworthiness on the part of "our informant." His comments show that he had no goodwill towards Lincoln and no willingness to give him the benefit of the doubt. As for trustworthiness, here's another version of the conversation, also attributed to the Baltimore Exchange:
Mr. Lincoln replied that, mathematically speaking, the troops could not crawl under Maryland, nor could they fly over it, and consequently they would have to come through it. If he was to follow the advice of Dr. Fuller, he would have no Government at all. France and England would recognize the Southern Confederacy, and his revenues would be broken up, and the Government would be worth nothing.
Whether this came from the same informant or not it certainly qualifies the other report. It wasn't all about "my tariff." It was about preserving the government and the country, and revenues were only a part of what was in peril. It was clear that secessionists were going to seize on the idea of the whole conflict being about "my tariff," but the context given here makes very different interpretations possible and likely.
The Baldwin meeting is sketchier than the Fuller encounter, since a bloody war had happened by the time Baldwin reported the quote, with Baldwin on the other side from Lincoln. Plus, the role of Robert Dabney, a notorious lost cause proponent, further muddies the waters. By the time Baldwin made his testimony, "What about my tariff?" was so much a part of the mythology that inserting it into his testimony may have been too hard for him to resist.
I haven't looked at the Baldwin-Dabney reports for a while. In general, though, I have a hard time judging the validity of a lot of these reports because the language is so flowery that it seems obviously unnatural to our ears. Plus, the person making the report usually portrays himself in hindsight as so clearly right about everything and the other person as so wrong or boorish that it's hard not to suspect some distortion happened between the conversation and the recording of it.