What is the law if one concluded with “Shomer Es Amo Yisrael La’ad” instead of “Upros Sukas Shalom” on Friday night or Yom Tov?
If he remembered within Kdei Dibbur, he is to recite the correct conclusion of Upros Aleinu. If he did not remember within enough time, he nevertheless fulfills his obligation, and is not to repeat the blessing. Nonetheless, after Davening, it is proper to repeat the words “Ufros Alein u Sukkas Shelomecha” without Hashem’s name.
 M”B 267:9
 Kol Bo 35; Elya Raba 267:7; M”B 267:9; Kaf Hachaim 267:9; Piskeiy Teshuvos 267:4
The reason: As there are communities who even initially recite the regular weekday Nussach. [Kol Bo ibid that Reb Shalom Gaon stated that in the Yeshiva they recite the regular Nussach]
 Kaf Hachaim ibid
The reason: This is due to reasons of Kabala, as explained in Shaar Hakavanos p. 69