Gagnetar is working on updating his Krystal mod for Half Life 2 to include a complete rework of Alyx's lines by the original Krystal voice actress, Estelle Ellis! Even after all this time, she sounds lovely as Krystal. For that extra bit of polish, Gagnetar even took the trouble to rewrite some of the lines to fit better with Krystal as a character in the game world, rather than simply doing a word-for-word recreation.
The mod apparently contains some additional features that Gagnetar wouldn't divulge, "everyone will just have to wait and see." Even I don't know what they are. He's planning to release the mod on Star Fox Adventure's 20th Anniversary, which probably means September 23, 2022.
Check out the example videos where Gagnetar shows off his ongoing work on the game and some commentary on different aspects of the mod as he encounters features in the gameplay.