Is your click handler actually called? Maybe you can put your non-working code in a meteorpad so that we can play with it?
ur not setting the key the. it should be:
set('b', currentTemplate.myReactiveDict.get('b') + 1)
also, if the event is being triggered by an included template, it won’t have the same instance context. that’s another reason why the second won’t work. the first one already has the template instance in scope–well, the reactive dict attached to it.