The settings page shows a list of preset search engines, but the settings page for each search engine is too generic: it doesn't show some preset values for the options it shows.
Being this the case, you could remove the preset list of search engines, and let the user insert the search engines he wants to have support for. The only difference from now is that the user would probably insert the name of the search engine in a form field that now is not present.
An alternative would be a wizard (multistep form) that would help the user in giving the correct informations (Which search engine? Google; which method do you want to use? File; What is the name of the file Google will look for? google3a55634fg.html; Done! Thank you; You are welcome).