After seeing this conversation back and forth for years, we just made a decision to keep it simple. I suspect the additional gratuities are added for the lounge staff - bartender, food service, etc. But that said, people are still getting different responses when they call in and ask who the tip covers, so who knows????.
Due to the $$ amount seeming really low, I tend to believe it is the "non-concierge host" team members in the lounge that the $8 covers. I still plan to tip for concierge how we always have. We use a rule of thumb of $100 x number of guests in stateroom x number of sailing nights. To illustrate - on a four night cruise for two guests - we will tip $800. (additionally, we will likely give each lounge food attendant another $50 and the bartender maybe $100 additional for the entire cruise - and would tip more for a longer cruise).
Some families tip higher, some tip lower. I don't feel anyone is wrong. We do a lot of our own planning and don't ask for much - but just REALLY enjoy the interactions we have with the team and the special effort they make to get to know us. From various polls I have seen, this seems to fall in the middle or slightly above from poll respondents. I'm sure this debate will continue for a long time. The recent change of adding the $8 per person might have made it more confusing. LOL
This should NOT be taken as advice or guidelines for your family. Everyone's experience with the concierge team is different, and I'm sure they are grateful for anything they receive. One change I have made over the years is to add the tip for the hosts to my credit card so they get it in their paycheck rather than cash. Knowing what a pain it must be for them to get the cash to their bank or credit union, it seems safer and more convenient for them. We still tip the food and bartender with cash. Not only is there really not a clear way to tip them on the bill, I want them to know that their service is appreciated. I think these positions are often overlooked.