You could make a few functions for accessing these - they are apparently fake arrays (like alarm[] is), therefore cannot be accessed through usual means (via variable_instance_).
You can also use
live_variable_add("some[]", function(set, idx, val) {
if (set) {
some[idx] = val;
} else return some[idx];
});
but do note that this defines a global variable, so inst.some[] wouldn’t work right, only some[].
For alarm, I have a good amount of code that makes it work largely-correctly, but I’ve not foreseen there being more instance variables like this.