No and your correct.
No, there is no other way. SNMP is the correct way to see the sessions (and more).
Yes, I too remember fondly the M4SENET-100 Telnet session to see the active sessions.... Trouble with that method is that it is so very limited in the data that it made available.
If the controller is not responding now and then, please take a close look at the comm handles you are opening and closing in your charts, that's the most common way for this sort of thing to happen. Each controller type has a limited number of TCP sockets (its in the respective manual) and once you use them all up, the controller will keep running the strategy and yet appear unresponsive since you can not connect to it.
(And if your strategy is still trying to open more comm handles, things will not get better.... I may, or may not have some experience in learning this lesson).