I think this should be really easy. All you need is a relation in your Staff sheet that uses the array and links to the project sheet. Then source the inline list from that relation and you are done. No filters needed.
Once you get that part working, then you can use maybe a simplified version of this method below to allow the user to select projects more easily. Something that would build a joined list of selected projects and then a button to save that selection to the user’s record in the staff sheet. But lets get the relation part working first.