Hello,
This is an extensive list. It will be difficult to rotate all these ninjas through the events. I see that some of these were in Treasure of the Sage the last time it came around (that is the purpose of the event, in some ways). You might be able to buy some of them next time it is back. A few of these do make irregular or semi-regular rounds still. For the rest, I will put in your request that they be brought back more regularly. I would also suggest that you keep an eye out to the events you don't normally frequent (again, like Treasure of the Sage for the next time it is back).