For the word deliverance /delivery, the original manuscript is only partially extant (deli, the first four letters of the word, is found at the end of a line in 𝓞). Perhaps delivery, if that was the reading in 𝓞, was spelled as deliveary since the printer’s manuscript reads deliveary. On the other hand, the 1830 edition reads deliverance. Here the 1830 compositor may have originally set delivery but then changed it to deliverance as a result of having the 1830 sheet (the 22nd signature) proofed against 𝓞 (see the discussion under Alma 42:31). Spacing between extant fragments of 𝓞 supports the longer deliverance, although delivery (or deliveary) could also fit here in the lacuna providing there was some minor correction in the line. When Oliver Cowdery copied the text from 𝓞 into 𝓟, he would have initially read deli, the first part of the word at the end of the line in 𝓞, which could have easily led him to misinterpret the word as delivery rather than the correct deliverance.
The printed editions have continued with the reading deliverance. Theoretically, either delivery or deliverance will work here in Alma 46:7. Elsewhere the text has occurrences of only deliverance (14 times); the word delivery occurs nowhere else in the textual history. The 1830 compositor could have been influenced by the lack of delivery elsewhere in the text, although we should keep in mind that there is nothing wrong with delivery. Moreover, there are no nearby preceding occurrences of deliverance that could have prompted the compositor to replace delivery with deliverance; the nearest preceding occurrence of deliverance is in the preface preceding Alma 17 (“their sufferings and deliverance”), 72 pages earlier in the compositor’s copytext, the printer’s manuscript. The word deliverance occurs quite frequently in the King James Bible (16 times); there is one occurrence of delivery in the King James Bible (in Isaiah 26:17), but for that occurrence delivery refers to the birth of a child.
Summary: The word deliverance, the reading in the 1830 edition for Alma 46:7, is probably the reading in the original text as well as in 𝓞, no longer extant; spacing in the lacuna and usage elsewhere in the Book of Mormon support deliverance rather than delivery, the reading in 𝓟; the fact that the end of the line in 𝓞 read deli could have led Oliver Cowdery to replace deliverance with delivery when he copied the text from 𝓞 into 𝓟; the 1830 edition ended up with deliverance most likely because for this part of the text the 1830 signature was proofed against 𝓞.