Should be ok now. There was a thread with the same title that was deleted twice. This shouldn't be a problem since there were two different thread IDs. But for some reason the thread ID got truncated - I have to look into why. So both entries ended up like this:
"Prime-exchange.ru - oбмeнный пyнкт элeктpoнныx вaлют in topic #546"
And that's a problem because the parser gets confused and doesn't find where the new (since last parse) entries begin in the modlog.
I've changed it to ignore the thread deletes when it's looking for new entries. It's already ignoring post deletes because those are obviously not unique. Now it will re-parse everything back to the last nuke or ban. Should be more reliable. Probably not 100% - technically it's possible for someone to get banned twice in one week albeit very unlikely. I might need to add something like checking 3 consecutive entries instead of relying on one entry.