Renaming a struct variable with special characters shows no warning

When you go to rename a struct variable, there are no warnings that indicate that you cannot use special characters, but they are immediately deleted if you try to use them in the variable name.

Found in 4.9.1 binary, 4.8.3, and Main CL: 2700641

1. Open Editor
2. Right click in the content browser
3. Go to Create Advanced Asset -> Blueprint -> Structure
4. Create a variable
5. Attempt to rename it with special characters

Result: Characters are deleted instantly when you press enter.

Expected: Warning would pop up indicating which characters are allowed in the variable name.