Ok guys, so far I have added everything you suggested (not everything, though). I will browse into the site to search some more games, like I said, any help is really appreciated by the community, just be sure the achievement is glitchy for a consistent number of people, not just for you.
DO NOT SEND ME PRIVATE MESSAGE EITHER ON THE FORUM OR XBOX LIVE, POST IN THE FORUM!
EDIT: Seems that players have problem with the DLC achievements of BlazBlue: Continuum Shift! If people confirm the achievements are unobtainable/glitchy I will add them on the list.