You're adding unnecessary things that don't need to be added.
I will explain to you how the event contents window works. Anything you put in there WON'T run/activate unless the trigger of the event has been, well, triggered. So if your trigger was set to action button, that means your 'change transparency = ON' will never actually run. It's a useless command in this case. Event commands in the contents window are all inactive until the trigger of the event is triggered, so whatever you put in there doesn't matter until the event is activated.
However, the options on the left hand side, such as the condition, graphic and autonomous movement, are all active at all times
if the event has met its conditions. So if you had 0 conditions checked on the event page, the event graphic is active and will show up in-game. However, if you chose a switch as the event page's condition, and that switch is turned off, the event page is not activated, and the event graphic will not show up. Effectively making it appear blank, until you turn this switch on.
This is what your NPC event should look like:
Now, in your other event, that controls the cutscene and text and whatnot, after you've done your thing (like dialogue), and are ready for the NPC to appear, you will turn this switch on (using the control switches command), and the event will immediately active and your event graphic will appear visible again.
There is no need for messing around with transparency when this is the quickest and most effective way of keeping an event invisible, and making it visible again.
All in all, you shouldn't 'read a little' on switches, you should read everything there is to find about switches and variables. Learn the program. Learn the logic, and then you can easily solve these problems yourself. Please look through our tutorial forum.