Scribe 2 of 𝓟 here wrote the things, which Oliver Cowdery later corrected to these things, probably when he proofed 𝓟 against 𝓞. It is possible that Oliver’s correction is due to editing on his part, but it is not unreasonable to assume that the original text (and 𝓞 itself ) read these things (in other words, Oliver corrected 𝓟 to agree with 𝓞). Elsewhere in the text, the things is always postmodified (usually by a relative clause or a prepositional phrase)—except in a single case:
What is striking here is that this passage deals with the very same topic as Mosiah 28:16—namely, the interpreters, “those two stones which was fastened into the two rims of a bow” (Mosiah 28:13). Both passages state that the person using the interpreters “is called seer” (note that these passages do not read “is called a seer”, which is what we expect in modern English). And most strikingly, Mosiah 8:13 uses the things to refer to the interpreters, not these things—which is precisely what scribe 2 of 𝓟 wrote in Mosiah 28:16: “and whosoever has the things is called seer”. The obvious similarity of these two passages strongly suggests that the things is the correct reading in Mosiah 28:16. In the discussion under Jacob 1:1, I listed many cases where the scribes mixed up the and these. In the list, I provided the only example where scribe 2 of 𝓟 seems to have mixed up the and these—namely, here in Mosiah 28:16! So if 𝓞 actually read the things in Mosiah 28:16 and scribe 2 of 𝓟 copied it correctly, then we have no examples where scribe 2 mixed up these and the. Instead, the problem would seem to have been Oliver Cowdery’s, not scribe 2’s. One possibility then is that Oliver mistakenly thought that the things was wrong in Mosiah 28:16 since this is the very kind of error he himself was used to making—and usually correcting. So maybe Oliver changed the things to these things in 𝓟 even though 𝓞 read the things. Further, we should note that earlier in Mosiah 28:14, there is an example of these things:
Thus it is quite possible that Oliver’s correction later in verse 16 was triggered by this preceding occurrence of these things. Notice that in Mosiah 8:13 there is no nearby preceding these things to prompt any such change in the things found there. Of course, one could argue the opposite: namely, the preceding occurrence of these things in Mosiah 28:14 means that verse 16 should also read these things. In fact, one could go further: the occurrence of the things in Mosiah 8:13 may be a mistake for these things; that is, the original text there read “and these things are called interpreters”.
Ultimately, it is very difficult to decide the original reading for either Mosiah 8:13 or Mosiah 28:16. Of some importance here, I believe, is the following: except for here in Mosiah 28:16 there is no evidence that scribe 2 of 𝓟 ever mixed up these and the; on the other hand, Oliver Cowdery had a persistent problem with these two determiners (there are 11 clear examples listed in the discussion under Jacob 1:1). In addition, the similarity between Mosiah 8:13 and Mosiah 28:16 is striking. The critical text will therefore assume that both passages originally read the things and that Oliver Cowdery edited the things to these things in Mosiah 28:16, being prompted by the earlier occurrence of these things two verses earlier (namely, in Mosiah 28:14).
Summary: Restore the things in Mosiah 28:16, which is what scribe 2 wrote in 𝓟; this reading is supported by the use of the things in Mosiah 8:13, a passage that deals with the very same topic; Oliver Cowdery apparently emended the things to these things in Mosiah 28:16 because the preceding text in Mosiah 28:14 read these things.