Why do you need it and how do you think it is best implemented in FontCreator? We want to keep things easy, especially when exporting the instances of a variable font.
My suggestion would be to allow a “Do Not Change Font Name” option. Eliminating the spaces in the name makes the font harder to find. And adding “regular” to the name can make the font name so long that sometimes you can’t see the full name in the font selection dropdown in many apps. And it’s just cumbersome.
A quick clarification: the name you see in an app’s font dropdown is taken from the font’s internal naming (Name table), not from the .ttf filename. So ABC-Regular.ttf shouldn’t affect what you see in most applications. If you do see “Regular” in the font menu, that comes from the Style name/Subfamily in Font Properties → Instances.
Some people deliberately change the font’s naming, and then they do want the exported filename to follow the updated name. So a single generic “Do not change font name” option might not be convenient for everyone.