Need help with setting up Glyph System.

I have multiple different potion effects made. I have the items made. I have the GUI made. Now the only thing i don't know what to do is make a way to connect the three.

Basically what i'm trying to achieve is a sort of trinkets like system. Where if you place one of the items into a slot it will give you a different effect based off of what item is slotted. I'm also looking to make this be stackable, as there are 5 separate slots in total.

(I'm trying to make like a glyph system)
 

tldr:

1. how can i have the game apply potion effects depending on which item is slotted into gui.
2. how can i keep the items slotted in the gui after gui is closed until items are removed.
3. is any of this possible or am i overestimating the limitations of Mcreator.