I know of no special term for that skill. I think most people would just make up a term that accurately describes the skill, such as the term you used, "tolerance of illegibility." For example, a linguist might write a report about reading in a second language. The linguist might write, "Some language learners have the ability to read beyond words they don't understand in order to comprehend the main idea of the sentence. In this report, such an ability will be referred to as 'tolerance of illegibility.'" This is only my estimation, though.

Hello Lily: There is a fundamental responsibility though, for a teacher to not use words for students, that they cannot explain. There is one exception to this, which is vital in the lessons that I use with all of my Chinese Students. I use songs, that the students can listen to in music videos. That way, they can hear how the words are pronounced, even if they do not know the meaning. This helps them know how to say the word. However, when I teach, I teach the meaning of every single word. What makes this easy, is that I get the lyrics to all songs on St. Lyrics website, and have the students read all the words. It is not quite fair, for a teacher to impart confused meanings. I do understand that teaching can be a difficult task; but that is why teaching should start simple, prior to introducing complex or difficult terms. Take this very moment for example. While writing, I am listening to the Peter Frampton song, "Do you feel like I do?" There is nothing extremely difficult in that vocabulary, and every one of those words is common in spoken English. Only when the simple and basic vocabulary is taught, can a student comprehend the language. Songs lend themselves to learning so much better than a mere text, because singing is repetitious, and that reinforces all learning. The Sound, the intonations, the emphasis, and the Rythm of music make pronunciation and speaking and expressing feelings a natural act. I try never to teach others, something that I do not personally know. ----Warm Regards, Bruce