While your project is admirable in its own right, and I've tried several ones that appeared throughout the years, Img Grabber remains my choice for such tasks. It's been around for years (whenever some changes were carried out for any website, say Konachan, the source would get an update almost immediately) and it includes a few dozen websites, Konachan being one of them. It even includes nhentai as a source (hehe).

It's versatile and it supports the three major operating systems, which is of particular importance for me since I use Linux most of the time.