“placeholder” means those devices have been migrated, or that there’s cloud-to-cloud integration already there. You should be fine, but to be sure, what wifi devices do you have?
That is the way it’s suppose to work, but since you have some custom handlers, you will need to get those Zooz drivers so that you can retain the same functionality that you had with the older device handlers, unless you want just the basic features. Here’s where you can find those drivers and get help with them: