I’m not sure that Dr. Martin Luther claimed infallibility for
anything outside of Holy Scripture, on which he based his doctrine
bible-researcher.com/luther03.html,
bookofconcord.org/confessionsandbible.php. Dr. Martin Luther referred to himself as " a stinking bag of worms," if I recall his statement correctly in context of whether or not he wanted the churches who sided with him to be named for him:
*“I desire above all things that my name should be
concealed, and that none be called by the name of
Lutheran; but of Christian. What is Luther? My
doctrine is not mine, but Christ’s. I was not crucified
for any. How comes it to pass, that I, who am but
a filthy, stinking bag of worms; that any of the
sons of God should be denominated from my name?
Away with these schismatical names! Let us be
denominated from Christ, from whom alone we
have our doctrine.” *
sermonindex.net/modules/newbb/viewtopic.php?topic_id=16469&forum=3
Just a plain Evangelical Christian, Dr. Luther, as I’m sure Ulrich Zwingli, John Calvin, Thomas Muntzer and John Huss would say about themselves, as indeed would St. Thomas More, Erasmus of Rotterdam and other Catholics of the day say about themselves. The difference was that Luther, in contrast with some other Reformers, kept the three essential sacraments ( Baptism, Absolution and Communion) and retained the Mass with certain adjustments
bookofconcord.org/augsburgconfession.php#article24. He didn’t want to depart the Church Catholic, but reform it ( nor was he the first to do so. I believe John Wycliffe of England is the one referred to as the " Morning Star of the Reformation"
christianity.com/church/church-history/timeline/1201-1500/john-wycliffe-reformation-morningstar-11629869.html).