Shalom u’vracha,
One who concludes the blessing of Asher Yatzar with the wording, “Who heals the sick of His people Israel,” instead of “Who heals all flesh and performs wonders,” has made two significant changes. First, he omitted the words “and performs wonders” from the conclusion. Second, he altered the wording of the blessing’s conclusion: instead of saying, “Who heals all flesh,” he said, “Who heals the sick of His people Israel.”
Regarding one who omitted and did not say “and performs wonders,” the poskim disagree as to whether he has fulfilled his obligation. Practically, the view of Eshel Avraham, Teshuvot Yechaveh Da’at, and others is that he has fulfilled his obligation.
Concerning the alteration of the established wording of the blessing—since he did not say “Who heals all flesh” but rather “Who heals the sick of His people Israel”—the view of Teshuvot Tzitz Eliezer is that he has not fulfilled his obligation. However, the words of Teshuvot Yechaveh Da’at indicate that he has fulfilled his obligation. There is also reason to maintain that he has fulfilled his obligation, since in a long blessing, if its conclusion was not invalidated, one has fulfilled the obligation.
Therefore, practically, one who concludes Asher Yatzar with the wording “Who heals the sick of His people Israel” need not repeat the blessing.
With blessings,
Rabbi David Ohayon