Dear Bob,
there are two things that are a problem, at least for me.
One is that many files on my HDDs are unsorted and untagged (from sharegroups, recorded by myself and so on). This is much more than 1 TB. All of them are on a drive with unsorted files. Nearly all of them have the work or composer in their file names (like: Dvorak, Symphony 8, Belohlavek). They are imported in the MC database only by these filenames. If I want to tag all unsorted Dvorak files, I'm searching in MC for the drive and Dvorak (Samsung Dvorak) and all Dvorak files on that drive are found by MC. But if several of them have the correct "Dvořák" in the filename they are not found because MC reads the as "Dvor a k". If I am searching "Dvor a k" it also not found.
Same with the kind of naming files that I use for decades now like "Mahler_Sinfonie8_Bělohlávek_BBC_Proms2010_1". MC can't handle "_" in the filename and reads them as "Mahler Sinfonie8 Be lohla vek BBC Proms2010 1". So I use the program Metadatics for this and the tool Filenames to Tags for that. If they are imported by MC the "_" is there but "Bělohlávek" appears broken.
Good new: double-click on a word with a special in MC works now and perhaps more important: MC works up to now without a problem with the new Mac OS Sequoia.
Frank