Since I cannot post in the other post you put I will post here.
Now I want to explain below with the understanding, that I could be wrong and if thats the case let me know.
He does have a similar problem however the thing that you say to do in the other post but respectfully it seems to me to be a bandaid and not a solution to the problem.
Basically Kunena 1.6 unlike 1.5 creates its own actual menu with menu items every time you install or upgrade, this is separate and apart from the main menu but it is an actual menu.
In the kunena template they actually create their own module position AND module for this menu and call it from with in kunena like a NORMAL menu in joomla.
The point of this is that when you click a link across the top of the kunena menu while with in kunena the tab will highlight to let the user know where they are. Now each of these menu items in the kunena menu OF COURSE have their own menu itemid.
So your solution to simply make it only use ONE item id with the item override breaks the system because then the menu items in the kunena menu DO NOT highlight, just the one on the main menu.
What I have been doing SINCE kunena has its own menu itemids is using ALIASES instead of direct links to point to the kunena menu itemids so that new itemids are not created to make it so it does not confuse ACESef.
What it is doing is if you don't have the itemid override turned on is recording the itemids incorrectly for the links and when it is turned on ignoring them all together.
The optimal behavior would be for the forums to to work as kunena intends them to. WHEN I switch to the basic router it records the urls itemids perfectly and the tabs work flawlessly thus proving it CAN work BUT I lose some of the url prettying that I get when the kunena router is on, so turning the kunena extension off is not optimal.
One thing is however, it seemed that the kunena 1.6 RC2 menu itemid recording with the 1.5.2 Kunena ACESef extention was working correctly AND ONLY stopped working when Kunena 1.6 STABLE came out. I think they added SEO stuff to 1.6 that was not in 1.6RC2, but I have shut that off and it still doesnt work...
So with the proposed solution in the other post the only options are either not have the new tabbing system work as intended and confuse the end user OR override the itemid and NOT have it work at all.
Is there any way we could just have it working correctly?
AGAIN if I am mistaken in my post I am sorry to have wasted your time please correct me if I am wrong.
P.S. you say to update tot he kunena sef extention 1.5.3 in your other post but it shows the latest version is 1.5.2 and indeed downloading and reinstalling it, it is only 1.5.2.
Please let me know...