How to read the band →
Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Royal
Royal has stayed fairly steady in American naming for generations. All-time it's been given to 24,394 U.S. babies, the 684th most common name by sound today, peaking at 1,217 in 2021, with 765 in 2025.
Royal has no common alternate spellings by sound.
Rising