Ultimate Aurelian

I think they could be potrayted through the mod's hero system. Choosing a hero from a later period unlocks Antigonid units.

Yes, as long as you check the original (because sometimes the summary is made up).

I think it's better to use wooden shield boss (there is basically no finds of metal boss from Ireland). Advanced and elite skins could have tunics; i dont think leather strap is accurate.

I suppose a new coin would be bright silver and rounder (no damage). If its in color i think you could a white monogram and white shield (shield has a wooden spina with iron boss ). Background can be a sort of medium blue (as seen in depictions of Galatians with blue cloaks).

First one seems a bit deformed. Second one is rounder and might just be damaged by age. I suppose it's not too much artistic license to make it round (specially since it would be brand new at the time).

Perhaps use for short range anti building attack like in Age of Empires 3 At least for regular buildings. For walls and forts undermining with reused villager pickaxe animation might be more accurate (palisades, gates and wooden forts get axe instead). That is if weapon switching is implemented ofc.

Britons had tattoos but there is no evidence for it in Ireland during this period; clubs dont seem to have been a common weapon either. Warrior women appear in some later Irish epics, although they are usually supernatural figures who teach heroes. Perhaps the promontory could train some allied units from Túathal's army like Romanized Britons, Gallo Romans, Britons Depending on the timeline that was chosen for the mod you could have Irish pirates (Scotti, Attacotti) but they only appear in fourth century. For dogs you could use the existing Wolfhound model (but probably not the mastiff, those are not native to the region) Celtic chariot reconstruction from this article arguing for Irish chariots. https://www.researchgate.net/publication/246543302_Iron_Age_chariots_and_medieval_texts_a_step_too_far_in_breaking_down_boundaries

For Irish trumpet player unit https://en.wikipedia.org/wiki/Dord_(instrument)#/media/File:Corno_in_bronzo,_da_loughnashade,_co._di_armagh,_I_secolo_ac._01.jpg Reproduction:

I think they might still be bronze (but last one has lost color with age). https://www.bladesmithsforum.com/index.php?/topic/41150-bronze-agehalberds-stabdolch-staffdaggerberło-sztyletowescepter-dagger/ https://www.alamy.com/stock-photo-the-uneticean-halberd-is-a-prehistoric-weapon-from-the-unetice-culture-140706092.html?imageid=C03632E4-2D98-4441-8EFE-BE92485E3D10&pn=1&searchId=5e99bb231a01012477d51a7e26e943ac&searchtype=9

I think number 3 (high kings) might be better Although maybe the vassals could be included as well

For appareance the fishing boat could be a dugout canoe. The merchant ship could be a sailboat carrying cargo. (Possibly a large hide currach) Scout ship could be a hide currach with no sail, carrying a couple warriors. Arrow/Javelin ship could be the same sort of sailboat as the merchant ship (but no cargo, and possibly put warriors on it).

For heroes you'd have to reuse some of the mythical AI names. Or have generic hero types (champion warrior, high king, maybe even a priest hero too although there is little information on religion). Túathal could probably be the heaviest equipped one (possible Roman and/or Romanized-Briton alliance). Have Romans ever been to Ireland? (Italian with english subtitles):

For unit ranks i think you could have something like Basic: No shirt, pants or loincloth. Plain shield Advanced: Simple tunic without pants Elite:Simple tunic with or without pants, cloak, painted shields. Champions: Torcs, finer tunics with pants, finer cloaks, painted shields. Perhaps headdress or some kind of leather/cloth armor for champions too.

I like the shields and clothing. My understanding is those weapons existed in an earlier bronze age timeframe. I dont think there were any iron versions.

I was thinking of a somewhat realistic silver coin (perhaps similar to Ptolemaic emblem, but silver instead of gold).