Right, but we read the word "eight" from left to right -- to me it is non-obvious that "eightwo" should be counted as two digits when (a) there aren't enough characters to actually make both digits and (b) there wasn't a single example showing this overlap expanded

But I suppose can see the other side as well: the wording makes it sound like any spellings of those digits _counts_ as a digit rather than should be _replaced_ by a digit.

However I think the ambiguity here made the puzzle more difficult in a non-fun way.