In the preface of Luther's Small Catechism, Martin Luther warns twice that people should be taught a fixed version of important church doctrine and that not a syllable should be changed (emphasis mine):
The honored fathers understood this well, and therefore they all consistently used one form of the Lord’s Prayer, the Creed, and the Ten Commandments. We should do as they did by teaching these materials to the young and the common man without altering a single syllable and by never varying their wording when presenting or quoting them year after year. […]
Second, after they have well memorized the text (of the catechism), then explain the meaning so that they understand what they are saying. Do so again with the help of these charts or some other brief uniform method of your choosing; adhere to it and do not change a single syllable, as said above concerning the text, taking your time with it. For it is not necessary to teach everything at once, but one thing after the other. After they understand well the meaning of the First Commandment, proceed to the Second, and so on, otherwise they will be too overwhelmed to the point of remembering nothing.
Luther must have been well aware that language changes over time; he insisted on having the Bible available in the common German people spoke instead of using the Latin Bibles that would have been more accessible to the people of a thousand years ago.
Did Luther ever acknowledge that his Catechism, or any of the other things like the Lord's Prayer, would need to have textual changes as well? At some point, the