Long titles

Use a smaller-text preset when a title needs more room

Duplicate your normal Generate Cover preset and reduce its title font size. Then open FanFicFare → Edit personal.ini and add a title-length rule near the end of the generate_cover_settings: block beneath [archiveofourown.org]:

    ${title} => .{40,} => Classics Small

40 means forty or more characters. Change it to suit your design.

Limitations

Character count is only an estimate of the space a title needs. Wide letters and long words can still wrap differently, so test several titles near your chosen limit.