The only thing I can say is that when I save the main options / font and custom legacy page, I have since years this message on top :
ERROR: CSS options must be enclosed in {}’s: “input bgcolor” = “(line-heigh:0.5)”. Please correct your entry.
I never found where such an error could be. But I don’t think it has to do with the title centering issue
Page titles are correctly centered, but not posts titles