>>78011802>have been outside of japan and forced to use english daily to function for a period longer than 1 monthRirika
Chloe
Lui
Haachama
A-chan
>noticeably ahead of everyone in JP in fluency, comprehension, and speaking abilityYou can hire all the tutors you want, but unless the individual incorporates their target language into their life, they will never learn the language beyond preset phrases and maybe a few hundred words (with zero contextual knowledge on how to use those words) if they grind vocab.
Most people won't acquire another language unless they have to, and I doubt hololive members have the time or want to put in the time considering they can buy a home and retire in less than 5 years simply by pandering to their native market.
If you look at the EN->JP side, really only Mori and maybe Ina have learned the language fluently while in Hololive. Kronii is passable conversationally. Everyone else is N5 or had several years with Japanese to become fluent(Bae, Kiara).
Not a lot of people are willing to do the grind, and to make it worse, nativeJP->EN or nativeEN->JP is the hardest language acquisition path due to grammar structure and phonology differences. Kronii/Ina having the highest non-native Japanese fluency of EN members isn't surprising either due to them understanding korean, which is near 1:1 grammar-wise to Japanese.