Here is script for those who seek function that let you filter out your library. This script can be accessed from Advanced Search menu since it easier that way.
To reduce the load of using this script, all your manga reading status and information will be fetched the first time you're using this...
Well i have done it myself in the past with 600+ reading list, searching through all pages just to miss it in the middle of it. Hence i create that script, much easier to search things. If you cant use script then maybe you could try third party apps?, idk any of it but they may have that...
Reviewing them one by one is way faster and more certain than asking the dev to make that feature available. Best chance is making your own script to do it. It is not perfect but at least it get the job done