Yes, I would like to add keyword support, but that’s currently impossible with the Photos library. Apple does not provide 3rd parties with any way to read, modify, or create keywords. I have made a formal request — maybe in the next OS. Don’t really know though.
There is no formal roadmap. I have a very large list of features and fixes that I review when preparing a release. I don’t publish anything because it changes a lot because of a) customer input b) new technologies Apple creates and c) how far behind I am 🙂
My goal is to move from large, infrequent releases to smaller, frequent releases.
In the case of keywords, there is no point even putting it on a roadmap because I can’t write the feature until Apple adds APIs to allow it.