From a textual point of view, the original syntax works perfectly well here, providing we interpret the intervening text as parenthetical, so that the main sentence reads as “she having been converted unto the Lord for many years on account of a remarkable vision of her father … never had made it known”. Similar usage of this type, but without any parenthetical statement, can be found elsewhere in the text:
Here in Alma 19:16–17, since the parenthetical having-clause (“thus having been converted to the Lord”) makes it rather difficult to process the complex syntax of this passage, the editors for the 1920 LDS edition emended the finite predicate “never had made it known” to a having-clause (“never having made it known”). They also added a connective and, thus creating a sequence of three having-clauses: “she having been converted ... thus having been converted … and never having made it known”. Besides simple examples like Mosiah 18:32, there are much more complex examples with the same original syntax as in Alma 19:16–17. Consider the following passage which has a sequence of six intervening present participial clauses before the main sentence is completed:
Interestingly, the words in this example have never been edited in any way to alleviate the complexity of the syntax. The critical text will restore the earliest text in Alma 19:16–17 since it is quite acceptable.
Another possible emendation worth considering here in Alma 19:16–17 is that in the original text there was a repeated pronoun she at the beginning of verse 17:
However, there seems to be little room between extant fragments of the original manuscript for the pronoun she to have occurred before “never had made it known” (except by supralinear insertion). Note further that the example from 3 Nephi 7:15–16 cited above does not repeat the subject just before the final main clause (that is, it does not read “he went forth among them”). Of course, there are examples where the subject is repeated, at least in the original text:
In this instance, the 1837 edition removed the repeated subject, the pronoun he.
Summary: Restore the original syntax in Alma 19:16–17: “she having been converted unto the Lord for many years on account of a remarkable vision of her father … never had made it known”; this kind of construction exists elsewhere in the Book of Mormon text, as in the complex example found in 3 Nephi 7:15–16.