The emotion wheel is just there as an aid to help people determine what emotion their character may be feeling, should people need it or find it useful.
Spikes only codify a spike in the emotion, so they can be RP'd however a player sees fit, as everyone deals with emotions differently. There is no procedure or "right way" to portray it accurately. It's left open to player interpretation. All that is mechanized is that that emotional state is spiked. What that means in the fiction is up to you/the group.
When an emotion spike is added, 1 spike is added and 1 spike is removed from the opposite emotional state. Everything else is referee fiat and is not codified in the rules. Meaning things would constantly be added and removed 1 at a time, sometimes things spiking out and causing roles to be made at disadvantage. And roleplaying the emotion spiking out to 5 like that would similarly be up to the player to decide how their character is to be roleplayed.
With the minimal design, the idea is that whenever something is not codified in the text, it's up to the group to decide how to handle it in their particular game, and the question implied by not having it in the text is more interesting than having a mechanic to determine it. It takes a bit of getting used to, for sure.