Can external events such as personal achievements, creating an artwork (or seeing one), or just learning about the path either by reading or listening to people who are more advanced on it cause/help progress?

It depends on what you mean by path I think. I have personally had a lot of insights that came from trivial things, but they were kind of like signposts along the way versus ego destroying cliffs.

Well, some suttas refer to people attaining stream entry or some other level of enlightenment after hearing a dhamma talk, i.e. the first talk after the Buddha's enlightenment.

I don't know if anyone really thinks in that way anymore, though. I would be interested to hear more.

I think at some point I saw and felt the path includes life in broad scope. Time on the cushion (or walking, standing, lying down) is very directed and precious, to be sure. Never take it for granted. However, I could just feel myself cycling at certain times within a certain part of the path. Depending on where I happened to be in a particular cycle, or where I was cycling within that, hearing/reading/doing something relevant may have just triggered the next, or an important insight. I think I've felt this happen in martial arts practice, in reading articles and hearing discourses.