In his editing of 𝓟 for the 1837 edition, Joseph Smith changed the present-tense are to were (spelled as ware). This change was either missed or rejected in typesetting the 1837 edition. Joseph’s probable intention was to have this reference to the twelve disciples agree in tense with the reference to them in the previous verse:
The problem here is that this previous reference in verse 7 reflects Nephi’s past-tense retelling of what he saw (“and I also saw and bare record that …”), whereas in verse 8, Nephi is directly quoting the angel (“and the angel spake unto me saying …”). Therefore the reference to the yetto-be chosen twelve apostles should be in the present tense in verse 8.
Summary: Maintain the present-tense reading of both the original and the current text in 1 Nephi 12:8 since here we have a direct quote of the angel’s words to Nephi: “behold the twelve disciples of the Lamb which are chosen to minister unto thy seed”.