REALbasic strings have a text encoding assigned and you normally do not care. For example if you pass a string from an editfield to a function like val(), you do not need to know what text encoding the string has. A function returns a string in the easiest encoding. The next function works with that encoding or converts it to whatever it needs. All transparent for you.
Now if one of the functions fails on this process, you are in trouble. Especially if it's a core function from the REALbasic runtime which is used in every app:
The len() function does not return the correct string length for strings with the UTF16BE encoding.
Please add this feedback item to your favorites on a good position as we need bugs like this fixed yesterday.