Welcome to ESOUI!
You are on the right track. Generally speaking when something is called "id" in the api, it is global and won't ever* change. On the other hand when it is called "index" it is local for the current context and may change at any point in time.
In the case of collectibles you can check the
list on the wiki to find the id you are looking for and then use that in your code.
*some things like ability ids have changed between major game updates, but that happens rarely