Folder Renaming Updates Filters
This has been suggested twice before, both posts being marked as REVIEWED:
"Wish the Filters get updated after renaming of Folders" (rank 65)
"Updating the folders reference in Filters" (rank 126)
Does this mean that they are scheduled to be implemented?
As remarked in the first post, you should add functionality to the "Rename Folder" code that iterates over all the filters & changes all references to the old folder name to the new folder name.
Referencing the second post, if each folder has its own unique internal identifier, then provided the folder name can be accessed via this internal identifier, store that with the filter, & use it to display the folder name when displaying the filter.