Programmer friend helped walk me through the bit I was missing from the tutorial skip-over. Effectively just that I needed to reference the interface my custom enum was held in as ITS event as instead of the custom one I made in the pawn. Blah Blah Blah. That got me over that one hump, that most importantly just let me set the enemy's alert state FROM the behavior tree.
Got a little ahead of myself trying to determine logic for differing states of alertness based off how long the player had been perceived. That hole involved him then trying to explain services to me and I spent too long trying to troubleshoot why my perception components weren't detecting me consistently. Tired brain won out and I decided I'll pick up the rest of the tutorial later and then find next steps.
UE5 First person dishonored-like stealth navigation and combat.
Round out basic mechanics and systems to then build a robust and polished level design to play around it.