The VFX like the chattering sounds when the characters laugh I asked around for and I'll try to tell you later, but if you can extract the sounds from the L2Ds, this site (https://apis035.github.io/bluearchive-spine/) is good
Viewing post in Where to Find Official Sound Effects?
Hello, sorry that this response will be a bit bare, but I found a way to extract the sounds if you're willing to follow through these steps. https://old.reddit.com/r/BlueArchive/comments/ufw8v5/i_need_help_extracting_all_...
Besides that, there is this site that has a bunch of RPGMaker-esque sound effects that might be useful (look under "Anime Like" for rough approximations): https://taira-komori.jpn.org/anime01en.html
Wow, you even found a nice site with lots of free SFX. Thank you.
As for Blue Archive assets, I managed to get voiceovers not only for the characters but also for the movie voiceovers and some SFX. I can't seem to extract what I was originally looking for though, so I will give up on that. Fortunately, these alone are a great help already, so thank you for showing me the way, I will use it well.