Hi. I´m also a collector, and share your preocupation on a simpler level. While I am not familiar with Plex (yet), I can organize an index of metadata on Excel (title, year, category, actors, etc.).
Relevant Skills and Experience
I´m American, a native English speaker with an equally large movie collection. I recently organized a similar index for my video collection, although the data is not attached to each individual file.
Proposed Milestones
$750 USD - Deliver the video index - if you need the metadata recorded on each video, I´ll need to study.