Here in 1 Nephi 19:1 we have two possible verbs, engraven and engrave. The infinitive verb form engraven, according to the Oxford English Dictionary, is now obsolete; the OED quotes examples from 1605 through 1713. There are quite a few examples of the past participial form engraven in the Book of Mormon text (24 in the passive, 2 in the perfect). None of these, however, have the variant engravened.
If we consider only the infinitive form, we find that engrave occurs only once but engraven five times. There has been some tendency in twentieth-century editions to occasionally replace engraven with engrave, as here in 1 Nephi 19:1. But in the current LDS and RLDS texts, the original engraven has been maintained for the most part:
The 1911 LDS edition changed all five cases of engraven to engrave, but the subsequent LDS edition (1920) reversed each of these five changes, undoubtedly by reference to some earlier edition since the engrave in Mormon 1:4 was not changed to engraven. This example of engrave in Mormon 1:4 may be an early error for engraven, although such an error would have been in 𝓞 since here both 𝓟 and the 1830 edition are firsthand copies of 𝓞 and both read engrave.
There is only one example of the simple past-tense form and originally it was engravened, but this form was changed to engraved in the 1837 edition:
This change of engravened to engraved was not marked by Joseph Smith in the printer’s manuscript, so its occurrence in the 1837 edition may be accidental since none of the other five occurrences of the verb engraven (the five infinitive forms listed above) were changed in the 1837 edition.
There is also one example of the verb engrave used as a gerund (in Jacob 4:1, “because of the difficulty of engraving our words upon plates”). And of course, there is the plural noun usage engravings (15 of them), which never take the variant engravenings.
Summary: Based on the earliest textual sources, there are six occurrences of the verb engraven, five as infinitives (including the two here in 1 Nephi 19:1) and one as a simple past-tense form (in 2 Nephi 5:32); there is one example of engrave as an infinitive (in Mormon 1:4); all other forms are based on the verb engrave.