The antonyms for the word "more unmistaken" can be ambiguous, uncertain, doubtful, or incorrect. When we use the phrase "more unmistaken," we usually imply that there is a higher level of certainty or accuracy. However, antonyms like "ambiguous" and "uncertain" suggest the opposite, indicating that there is a lack of clarity or precision. Likewise, "doubtful" implies a degree of skepticism, while "incorrect" means that something is wrong or inaccurate. So, if you want to convey the opposite of "more unmistaken," you might use words like these to suggest a lower level of certainty or accuracy in what you are describing.