Thanks for the response kepper! I went back through and waggled information around in my head until I finally figured out that Hoplomachi Bruttii were actually Bruttii Swordsmen. It really confused me since the EDU file usually references the name that shows up in game. I don't speak Greek or Latin and only barely get the basic usage, so seeing Hoplomachi was making me automatically think hoplites. At any rate, here are the screenshots of missing AOR units:
Arretium with the following units missing:
recruit "aor etruscan hoplites" 0 requires factions { seleucid, } and hidden_resource aor_etruscan
recruit "aor etruscan cavalry" 0 requires factions { seleucid, } and hidden_resource aor_etruscan
As you can see, they show up on the description as recruitable but are not available to queue. I double checked and do indeed have the Hoi Lakedaimonioi kai hoi Symmachoi government building constructed here.
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Rhodos with the following unit missing:
;;recruit "merc rhodian slingers" 0 requires factions { seleucid, } and hidden_resource aor_greek and hidden_resource special_hr_2 and not hidden_resource capital
From the building browser, as I don't actually have the building here yet to tell if they for sure don't show up. I've not seen this unit in game either, other than from the mercenary panel. Is it supposed to be an AOR unit that you can recruit? It would be awesome if yes, sad if no. The EDB file is kind of confusing in that regard.
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Kydonia with the following unit missing:
;;recruit "merc cretan archers" 0 requires factions { seleucid, } and hidden_resource aor_greek and hidden_resource special_hr_3 and not hidden_resource aor_mace
Same question as the Mercenary Rhodian Slingers, but even more emphatic about them being recruitable. I'd really love to be able to train these guys, even if I have to drag them across the globe to retrain them. 
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Gergovia with the following unit missing:
recruit "aor keltoi ambacti" 0 requires factions { seleucid, } and hidden_resource aor_gaul
After taking the screenshot I realized that I actually had the Hoi Lakedaimonioi kai hoi Symmachoi built in Treveri and Massalia, which should also be able to build Ambacti I believe, but don't have the option. It just needs to be a settlement with Keltoi resources, right?
Again, many thanks for your timely response kepper! I hope you can help me figure out the problem and that there is a simple solution.
Best regards,
Deathkorpsman