Question: When following a guiding track being played to verbally recite a sūtra, is it alright to miss a few words when catching my breath, while still reciting mentally?
Answer: It is alright, unless you are reciting for others to hear without a guiding track, which will then require every word to be verbalised clearly, so that there is no loss or change of meaning in that heard.
Of course, it is best to recite verbally throughout clearly, if that was the original intention. With practice to pace breathing, this can be done. It is alright to recite without a guided track too, with personal pacing. Otherwise, totally mental (i.e. silent) but sincere and mindful recitation is alright too.