C# の場合どうなんだろうと思って調べてみたら、text elementsって表現してた＞＜

StringInfo.LengthInTextElements Property (System.Globalization) | Microsoft Learn https://learn.microsoft.com/en-us/dotnet/api/system.globalization.stringinfo.lengthintextelements?view=net-8.0#system-globalization-stringinfo-lengthintextelements

"The number of base characters, surrogate pairs, and combining character sequences in this StringInfo object."