These Korean voice actors sound familier...

So turns out quite a few VAs from the Korean side share voice roles with characters in Library of Ruina. And these are only the ones I know.
Xiangling, Barbara, & Gloria: Yun A-yeong (윤아영)
Hu Tao & Hod: Kim Ha-ru (김하루)
Noelle, Keqing, & Eileen: Lee Bo-hee (이보희)
Rosaria & Binah: Kim Bo-na (김보나)
Venti & Gebura: Jung Yoo-jung (정유정)

[@alexanderchon9058]

Thought of Gloria helping Xiangling with the cooking... MY GOD IT IS SO CUTE!!!

[@NaroOwO]

Did you know?? The purple tear and Paimon(Korean) shares the same VA

[@ethancolbourne5908]

They turned the HAG into a CHILD!?

[@the_fenix_3247]

I had a feeling that Xangling sounded similar to someone, also is sad that Genshin's Xiao is not a pyro character

[@redlightu]

Lol, yeah. Imagine LOR's Xiao as a 5-Star Pyro polearm user. Be pretty awesome.

[@redlightu]

There's probably more I don't know about yet, Library of Ruina's Guests' VAs haven't been entirely revealed, so there could be others.
Also, there is Venti, who shares VA with LOR's Gebura but I don't have Venti to compare.

[@cherry414]

Gebura as Venti oh my lord 😦

[@adityawiryawan560]

Hod being one of best girls even in other games

[@Aceleo209]

Adios Albedo. Rosaria is my new main. Binah supremacy forever!!

[@AverageHeathcliffSimp]

but Albedo is Oswald!!

[@user-zs4ti9oo9h]

진짜로 같기 때문.,

[@fabiola2529]

Thanks i'm really hyped to know all of this now!

[@bobburgers3880]

Gebura is venti lmao

[@Flygoniaks]

Huh, small world (or perhaps small country).

[@DrSlenderGaming]

A question remains, who's roland?

[@redlightu]

Beats me, either he's going to be one of the many future characters, or he's an NPC.

[@EepaBeepa]

@@redlightu being an NPC is the most roland thing ever

[@vladsoloshchenko5551]

​@@EepaBeepaSome secret NPC with 30 hp that will help you(And dies, cuz he uses his patron librarian page

[@notloopers1110]

NO
IT CANT BE
GENSHIN TAINTS EVEN LoR?
NOOO-

[@redlightu]

Relax man, it's just the voice actors. They've taken many roles from different games, Genshin's no different.

[@ARatherEdgyEnglishWangcore]

Funny to say that when LoR actually predates Genshin by a few months. So they were here before Genshin was even a thing.