While there are multiple ways or ideas on how to keep track of video file metadata (I am more interested in watched/not watched since all images are stored on the same NAS as actual video files and there is no need to download them from anywhere and save locally) they all have some issues.
Local data saving sometimes got deleted by Apple OS to clean some space while holding data on iCloud (or any other online place) require you to be online for that to work and at some point will expect you to pay for that cloud service because free version will not be enough.
There is another simple way how to sort such problem - save data locally into the SQL database. All that is needed for that is to know schema that Infuse uses and username/password for your local database.
This might be more advanced user feature because of the need to know how to set up that database, etc., but on the other hand, it can give a unique opportunity to such advanced users because they would be able to create they own software to interact with the same database for whatever needs they require.
I would assume that adding direct SQL support is more straightforward than adding metadata storage in iCloud, while the user base for that functionality might be much more limited, but what such users could get out of it would be more beneficial.