Here we have two passages where an original subjunctive were was changed to the indicative was in the 1837 edition, probably as a result of editing by Joseph Smith (although neither change was marked by him in 𝓟). In the first case, there is evidence elsewhere in the text for both “save it were” and “save it was” (for discussion regarding the variation for that phrase, see under Alma 17:38). Similarly, in the second case there is evidence for either were or was (for that, see under Alma 8:31). In both these cases here in Ether 15, the critical text will restore the original subjunctive were.
Summary: Restore the original occurrences of were in Ether 15:12 and Ether 15:14; in both cases, either were or was is theoretically possible, so we follow the earliest reading.