Fuzzy is probably a simple bug... and in fact I've improved the matching quite a bit ready for the new build.
(Fewer false positives, less triggers from things like punctuation and numbers, better phrase detection)
So I'll get a new build out shortly.
Re: the prompt window, that's a tricky one - I ask the current application where its caret is, and then try to pop up just to the right and below. In most cases the reply seems to be quite good, but for instance in Thunderbird I always get the top-left of the edit window. I'll do some more research.