> It can't even find anything in my own posts.

Ditto. I have seen this as a crippling deficiency in the Facebook platform. Not being able to search properly in my own posts or in the groups I'm a member of really sucks. For all the engineering prowess, open sourced tools, etc., shown by Facebook, the lack of a working search makes the company seem incompetent from the top down.

Sometime ago I started storing important information (like others links, my own comments, etc.) outside of Facebook where I can find them easily. I also started a Facebook page and added Notes into it to make it easier to document, find and share things. It seems ridiculous that I'd have to do this just to have access to information, but that's been the sad state for years.