ProjectSeleukid - how do you solve a problem like Magnesia?

Illustration from Ancient Warfare Magazine

I have been mulling over the dispositions of the Seleukid army in the accounts of Livy (37.40) and Appian (Syrian Wars 32-3) to try to establish both the initial army list for Project Seleukid, and also the shopping lists for Andrew and I. 

The table below breaks down the deployments of each named unit according to Appian and Livy into left flank, centre and right flank commands.

Units	Left	Centre	Right	Unallocated
Companions	Appian Livy 1,000
Agema	Appian		Appian Livy 1,000
Argyraspid cavalry			Appian
Cataphracts	Appian Livy 3,000		Livy 3,000
Galatian cavalry	Appian Livy 2,500		Appian
Tarantines	Livy
Dahai and other mounted archers			Appian 200 Livy 1,200	Appian
Arab camelry	Livy			Appian
Elephants	Livy 16	Appian 22 Livy 22	Livy 16
Scythed chariots	Livy			Appian
Argyraspides			Livy 6,000
Macedonian phalanx		Appian 16,000 Livy 10,000
Galatian foot	Appian Livy 1,500		Livy 1,500
Kappadokians	Appian Livy, 2000
Cretans			Livy 1,500	Appian
Neocretans	Livy 1,000
Trallians	Livy 1500		Livy 1,500
Karians and Kilikians	Livy 1,500			Appian
Pisidians, Lykians and Pamphylians	Livy 4,000			Appian
Elymaian archers and Kyrtian slingers	Livy 4,000		Livy 4,000
Thysian archers			Livy 2,500
Unnamed tribes	Appian Livy 2,700
Unnamed skirmishers		Appian	Appian

Of the two sources, Livy gives the much more precise breakdown, but neither author accounts for the total number of 70,000 given for the Seleukid army as a whole. 

A couple of issues remain:

1) Argyraspid cavalry are never mentioned in any Seleukid army except in this battle, where Appian places them on the right. The elite argyraspid infantry are located in the same place by Livy. Are they the same thing, and is it an error on Appian's part, or on the part of a copyist at some point in history.

If the unit in question is just the silver shield phalangites, their deployment on the right flank, away from the rest of the Macedonian-style phalanx, is unusual. However, Livy's numbers for the two classes of phalangites equals the total given by Appian. 

Moving forward we might follow Livy here, and dismiss the argyraspid cavalry as an error.

2) How were the Trallians armed? Whether assuming a Thraco-Illyrian origin, or seeing them as coming from the city of Tralles, I had presumed they would appear as thureophoroi. However, I am now leaning toward's the alternative theory put forward by Duncan Head that they may be slingers. Sources unclear, but they were brigaded alongside Cretan/necretan archers on both Seleukid flanks, and also with Cretan archers on the Roman side. There is a long tradition of slingers and archers operating together and they would seem to fit within this. 

3) Where are the Thysians from? They are archers, so perhaps they were Iranian, but I can find no other refernce to them.

If anyone can shed further light on these issues, I'd appreciate any suggestions!

Army lists

The current thinking produces the following Hail Caesar army list (coming in at 723 points):

The unit profiles for a Seleukid army using the Fantastic Battles rules might then look like this: