Ooooh I love Astronauts!!! And while I don't know your personal taste in voicebanks, I do think the song is more suited for gentler vocals and I think it would sound good with just about any soft/whisper voicebank personally.
If you haven't tried her out before, Anna Nyui has a really pretty whisper-y type voicebank named Milky. It's a tripitch VCV but I still find it very easy to get emotion/expression out of.
Also, I'm definitely biased towards my fav girl Rinne Tsubasa but both her "MI" and "WS" voicebanks are really good options for soft vocals. WS is a whisper on all 5 pitches, and MI is soft and whispery in low to mid pitches and becomes more normal (but not at all powerful) in higher pitches, and includes multiple falsetto pitches. plus an endless amount of breath and vocal fry options <333