QUOTE
...how do you know they are enabled?
My bad, incorrect terminology. If a font is installed but not one you want to use, it can be turned 'OFF' by selecting it and using the "Disable.." menu item in the File menu or the same item in the 'gear' button on the upper, left-hand part of the Font Book window. So, "OFF" means 'disabled' and nothing showing means 'enabled'. As long as the font name appears in the Font Book list, it's installed, the only choice then is to have it on or off. If it ain't "OFF", it must be 'on'!
Of course, if it ain't even there, I have no idea whether it's on or off!
Glad to know you've found a way to get things back in a 'working' manner, hope it lasts!
BTW, what is the name of a Korean font as it would appear in the Font Book list? Never mind, I have an eBook somewhere that has that info, I think..