Although your approach to it much better, they may as well have called is XERXES by combining letters that are and aren't in the phrase with some permutation.

There is no link between the name "Evolved Sign Momentum" and "Lion". They can call the thing what they want, but they're making up the link.

Could have called it Eve

Or SignUp. Even makes a good paper title: SignUp for faster training by evolving the learning algorithm.

Your "maybe" is grossly unnecessary! Get an editor, sir!