Mine often won't touch a new toy for days, weeks, months...

I think this is especially true for young keets in their first several months in your home. They are still a little cautious, and they don't have much experience with toys and what can be done with these things.

Have you tried moving the toys around? Sometimes that will cause them to get interested. (But don't move them too often, or you might make your keets constantly nervous. Give them a couple of weeks, or more, with any arrangement.)

As long as they are active and chirpy, I wouldn't worry too much.