In this passage, scribe 2 of 𝓟 took over for Hyrum Smith after Hyrum had written they must. Scribe 2 wrote unavoidably remain, which ended up creating for this past-tense context what seems to be a difficult reading: “they must unavoidably remain in bondage until now”. Here king Mosiah is referring to the people of king Noah (subsequently, the people of king Limhi); he is basically saying that these people would still be in captivity if it hadn’t been for the intervention of the Lord. The use of “until now” at the end seems to require the perfect “must have remained”. When we consider other places in the Book of Mormon text where the phrase “until now” occurs, we find that in each case the surrounding passage is either in the simple past tense (one time) or in the present perfect (five times):
On the other hand, as David Calabro points out (personal communication), there are a few instances of “until now” in the King James Bible for which we get the present tense instead of the expected present perfect:
In fact, the Revised Standard Version (1952), a conservative revision of the King James text, translates the first two of these passages with the present perfect:
(In the case of 1 John 2:9, the RSV replaces even until now with still, which permits the presenttense is to be maintained: “he who says he is in the light and hates his brother is in the darkness still”.) In accord with the King James usage, one could argue that what Hyrum Smith and scribe 2 of 𝓟 jointly wrote here in Mosiah 29:19 was actually correct.
The problem is that Oliver Cowdery, when he proofed 𝓟 against 𝓞, corrected remain to remained. But in his proofing, Oliver Cowdery did not add the expected perfect auxiliary have; thus he ended up creating in 𝓟 an even more difficult reading: “they must unavoidably remained in bondage until now”. Now the question here is whether Oliver was correcting 𝓟 against 𝓞 or consciously editing the text. The problem with the second alternative is that if Oliver had been editing, he would have probably added the have in addition to the past-tense ending -ed. It seems more likely that here Oliver was correcting 𝓟 to agree with 𝓞. Obviously, Oliver did not notice the incongruity of must remained, his corrected reading in 𝓟. Similarly, the early editions kept the difficult corrected reading with remained. Finally, the 1849 LDS edition, edited by Orson Pratt, restored remain, undoubtedly because the modal verb must needs to be followed by the base verb form remain rather than the past participle remained. On the other hand, the 1858 Wright edition inserted have before remained, thus retaining Oliver Cowdery’s corrected remained (the reading of the 1840 edition, which was the copytext for the 1858 edition). The have was removed from the 1908 RLDS edition (it was not in 𝓟). But the 1953 RLDS edition restored the have since it seems necessary.
The question remains: why did Oliver Cowdery miss the have in his proofing? One possibility is that his copytext, the original manuscript, was missing the have, and therefore 𝓞 read precisely as Oliver corrected 𝓟: “they must unavoidably remained in bondage until now”. The actual original text, which one could presume Joseph Smith correctly dictated, may have read “they must have unavoidably remained in bondage until now”. The phrase must have would have most likely been pronounced as /mvstßv/. But given that the following word unavoidably /ßnßvbidßbli/ began with two schwa syllables, including one of the form /ßv/, the scribe in 𝓞 may have missed the contracted /ßv/ attached to the preceding must, thus writing down Joseph’s dictation in 𝓞 as “they must unavoidably remained in bondage until now”. Scribe 2 of 𝓟 tried to deal with this difficult reading by omitting the -ed ending, just as Orson Pratt (or the 1849 compositor) did for the 1849 LDS edition. In other words, Oliver restored the -ed ending in 𝓟 since it was in 𝓞.
Now if have was in the original text for Mosiah 29:19, then the have could have come either immediately before or after unavoidably. When we consider other cases of “modal + perfect have”, we find evidence for placing the adverb either immediately before or immediately after the perfect auxiliary have (given that a choice is possible):
adverb before the perfect have
adverb after the perfect have
The adverb in Alma 9:11 is the same unavoidably that appears here in Mosiah 29:19, thus supporting the 1858 word order in Mosiah 29:19. Even so, the other word order is clearly possible. And what is perhaps more significant, placing the original have before unavoidably explains more readily how the have (as the contracted /ßv/) could have been lost as the scribe in 𝓞 took down Joseph Smith’s dictation.
Another possible interpretation for the two readings in 𝓟 has to do with the fact that after writing they must, Hyrum Smith turned the copywork over to scribe 2 of 𝓟, who wrote unavoidably remain (which Oliver Cowdery later corrected to unavoidably remained ). If the have was in the original manuscript, it could have been accidentally omitted at that very point where scribe 2 of 𝓟 took over for Hyrum. When Oliver came to proof this passage in 𝓟, he noticed that remain should read as remained, which he then corrected; but in making this correction, he could have missed seeing the have that preceded unavoidably in 𝓞. If the have had come after unavoidably, it is less likely that he would have missed it in correcting 𝓟. So it appears more likely that the original have preceded unavoidably (providing 𝓞 had the have).
As noted above, the initial reading in 𝓟 (“they must unavoidably remain in bondage until now”) is possible. Yet 𝓞 seems to have differed in some way from that reading, thus motivating Oliver to correct the reading in 𝓟. The original reading that best explains what happened when 𝓞 was copied into 𝓟 is that the original text read “they must have unavoidably remained in bondage until now”. We cannot be sure whether the have was actually written down in 𝓞, but the critical text will assume that it was in the original text itself.
Summary: Restore in Mosiah 29:19 Oliver Cowdery’s corrected remained in 𝓟; in addition, the perfect auxiliary have seems to have been omitted before the adverb unavoidably, either when the scribe in 𝓞 took down Joseph Smith’s dictation or when scribe 2 of 𝓟 took over for Hyrum Smith in copying the text from 𝓞 into 𝓟; the most plausible reading for the original text in this passage (the one that best explains the two incongruous readings in 𝓟) is “they must have unavoidably remained in bondage until now”.