[e12e]

Well, how long is the sequence "a<Backspace>". It's two characters and one, two or zero letters?

[rnhmjoj]

This has been covered a few times before. See this for example: https://mathiasbynens.be/notes/javascript-unicode

Data.Text seems to recognize symbols made of several codepoints (like emoji) as one but still counts diacritics and combining characters as different symbols.