Hi Vince,
I've never considered using variables in the <snmp-device-notifiers> section of an alarm point probe, but it looks like it might work.
One concern is that the Notifier variable is substituting for a quoted string. I'm wondering if the quotes are making the transition, and whether it's possible to escape them with backslashes if not (substituting \" for a plain ").
The other thing you might try (and you may already have done this) is to wrap the variable name in braces, like
Notifier1: "${Notifier}:${Delay}:${Repeat}:${Count}"
However, the description in the documentation, in enclosing the value of the SNMP device notifier in quotes, implies that we're looking for a literal, so I won't be surprised if variables don't work at all.
Have you tried substituting the variables only for delay/repeat/count, and leaving the Notifier as a string?