I think you should just make sure to do rikos if anything, might not be necessary though. Pretty sure I did the other 2 in post. Save on another file just in case, but fairly sure you won't be locked out

you may miss riko's 'Connected by the Abyss' achievement with that character, since she's replaced by reg on 4th layer after attaining white whistle, my cousin got locked out of her quest because they postponed it and didn't know it was going to be replaced later