When using component glyphs, after modifying the name of the referenced glyph, the name at the reference location does not update automatically.
The text you can enter in glyph metrics fields, such as LSB and AW, is currently treated as free text. That means it is not automatically updated when a referenced glyph is renamed.
Most parts of FontCreator use deeper internal links to glyphs, so renaming works there, but these metric expressions do not. For now, you will need to update those references manually after renaming a glyph.
We may improve this in a future release.