Yes, that's what I mean. I know how to delete misspelled words. An example, I already have a keyword percussion, correct spelled with lower case. I don't want to delete that keyword. Now I want to add Pendrecht to a photo, starting with upper case. So I start typing P (uppercase) e (lower case) - now Photos changes the upper case P to lower case because it apparently but wrongly expects I want percussion. And it doesn't change it back to upper case when I continue typing, so I end up with pendrecht. If it's not the first keyword, then it's possible although tedious to edit the p back to P. But if it's the first keyword on that photo, then I have to edit it with the Keyword manager to correct it, for directly editing just deletes the first character. Sigh.
I only want that if I type upper case, that it always will be upper case. And if I type lower case, that it always will be lower case. Why is that not possible? In the end I succeed to get what I want, that's not the problem, but it requires much extra editing. 😟
Oh, and I already have Correct spelling automatically off. So that doesn't do the trick.