Koko has only been with you for one week, that is not nearly enough time for an older rehomed grey to settle in and feel comfortable, give her plenty of time and be patient with her for this process can take weeks, months or even a year. Sit by her cage and talk to her, tell her about your day and what you are doing, she may understand more than what you think she does, offer her treats and do not be too worried about her eating habits right now as you can do more to correct them later, right now you want to work on building trust.
The toys you are offering her are new to her and when she gets used to them and realizes they are not out to get her she may start playing with some of them, in the meantime you can play with them yourself and pretend you are having a good time so it will entice her to want to do the same.