toUpper: 32 problem chars
toLower: 66 problem chars

toLowerOfToUpper: 14 problem chars

Problem chars true: 73/304 - I/i - İ/i̇
Problem chars true: 105/304 - i/i - İ/i̇
Problem chars true: 223/7838 - ß/ss - ẞ/ß
Problem chars true: 304/73 - İ/i̇ - I/i
Problem chars true: 304/105 - İ/i̇ - i/i
Problem chars true: 304/305 - İ/i̇ - ı/i
Problem chars true: 305/304 - ı/i - İ/i̇
Problem chars false: 912/8147 - ΐ/ΐ - ΐ/ΐ
Problem chars false: 944/8163 - ΰ/ΰ - ΰ/ΰ
Problem chars true: 7838/223 - ẞ/ß - ß/ss
Problem chars false: 8147/912 - ΐ/ΐ - ΐ/ΐ
Problem chars false: 8163/944 - ΰ/ΰ - ΰ/ΰ
Problem chars false: 64261/64262 - ſt/st - st/st
Problem chars false: 64262/64261 - st/st - ſt/st