CB only uses multisell, not buylist.
this is understandable, but the ability to sell things through CB is made as a buylist:
data\scripts\handlers\communityboard\HomeBoard.java
here is the command in the file
else if (command.startsWith("_bbssell"))
{
final String page = command.replace("_bbssell;", "");
returnHtml = HtmCache.getInstance().getHtm(player, "data/html/CommunityBoard/Custom/" + page + ".html");
player.sendPacket(new BuyList(BuyListData.getInstance().getBuyList(423), player, 0));
player.sendPacket(new ExBuySellList(player, false));
}
it indicates what is used buylist.
player.sendPacket(new BuyList(BuyListData.getInstance().getBuyList(423), player, 0));