As long as you're not experiencing any problems with iTween or your game is very performance dependent, there's no need to switch from a working system. The reason why it's not suggested to use anymore is because it hasn't been updated in a long time (2013 I think was the last time) and there are alternatives that do a better job at tweening animations (like DOTween or LeanTween), so I would only recommend to switch to them when you start a new project.
I use iTween for years and never had any problem with it. It would not only take forever to change all actions to a different system but the difference would also not be that noticeable.
If you only have like a handful of iTween actions you could start learning another approach, but I say stick to iTween for your current project and switch when starting a new one.