[parkher]

Yes, I am doing exactly that - one change at a time.

BTW, there are many many messages that have to be ignored, at least in English language books:

"2077 lines that end without punctuation"

Here is nothing to fix - direct speech ends usually this way:

"Hey!"
"What?"
"Nothing."

This would give three such messages.
But in many other languages, it is a useful message.

Perhaps PerfectEpub should look one character back beyond the final ",”,', ’,», etc.?
So that both these cases are found to be correct:
"Nothing big".
- Nothing "big".
However, just " without . on other side - wrong.

The thing is, because this message now has to be ignored, some legitimate cases where punctuation is really missing might be skipped as well.