So err, personally I think all euro caves need readjusting. BC hits too strong for what it is, used to be THE go to lvling place for warrs with halfmoon and even before then in thrusting lure spots. Make sure exp there is decent enough. ST also used to be decent, again mobs hit a bit too hard here.
Maybe the issue is that euro caves feel too lack luster to hunt in compared to the newer places. A buff to their exp may seen people heading back to those caves rather than everyone clogging up the new ones.