Blog Commenting is good if you are careful enough. But don't do anything in automated way in SEO. It may give temporary benefits but in long run you have to pay the price .
Google use a range of heuristics when determining spam. It all comes down to 'does it look natural' (i.e. is it within statistical norms). A vast number of links all from blog comments, and 3 from other sources suggests what? A lucky coincidence? Or someone who has purchased 'BlogSpammer V9'?
I don't think they can track your comment builder because anyone can do the comment for your site even you don't ask them.
Its too obvious when a random comment appears on a blog - I have had several of start up blogs (which I spin), and in particular when you are starting to get noticed in the search engines, you can see a ridiculous spam comment coming a mile away - and its blocked instantly. Or better still WP blogs install Askimet, which automatically finds the spam. Dont do it - Thinking your time has been spent well doing automatic comments is just wasted. Instead put the little bit of effort in and find a quality place to get some good links on. Thats what your competitors are doing - and thats how they will get ahead of you
don't build blog comments direct to your sites,, build blog comment to your backlinks to make juice backlinks