you are correct that LogicPro unfortunately only offers three keyswitches per articulation, it used to only offer one!
But still three is often not enough. You can write your own Scripter scripts. Its actually not that difficult to write a simple scripter script that will insert 5-6 keyswitches per articulation ID. I can do a tutorial on that if there is enough interest. Its obviously not as easy as adding them directly to the articulation set, but once you do one script like this, the 2nd and 3rd scripts would be relatively easy. I can write a script in literally 10 minutes that will handle the keyswitches for a Synchron instrument...its not a big deal...but it does require a little bit of scripting prowess, which a lot of orchestrators don't have and don't have any inclination to learn...so I get that...