ah
thought you're throwing rhetorical questions here. .-. sorry for that
soo, image-fails-loading one explained above, the other one I think would probably be problematic to implement but that's for grumpy to decide. Searching for other instances of already existing pages wouldn't add anything new because all chapters of the comic in question end up on a single comic page and we don't have any "member galleries" or "full volume of mixed mangu" stuff for which I suspect that feature was made for.
I actually haven't noticed they have another option for reverse image search of images from outside of the site, that I guess might make sense to find comic titles or particular chapters if you were to find an uncropped comic page somewhere on the internet, but you can already use google search for that (and probably with a much better result than whatever we could be able to implement - google has indexed all major aggregators, so your chances of finding that page are much bigger there).
well said indeed, in any case , search by google can help most of the time, but not every time,
thats why i prefer image search at specific place to search it, i could reverse search cropped image and find similar cropped image that people posted in their twitter, or memecenter or 9gag and etc instead the original,
while search in the specific site, like hentai crop image in hentai site could lead me to the info where it from, what manga it is and etc, and sometimes not