Advice on my EIR army composition, please.

[Tim Haslam]

Ive built up a rather lovely Auxiliary force using the stunning Victrix figure range, made a few conversions etc.
But I’m considering adding a German tribal contingent, especially as Victrix also make these. That being said my favourite are still Foundry, but prices are prohibiting that choice.

My force will primarily be used to play WAB but also Infamy at some point.

So, my question, what (if any) tribes actually acted as mercenary or allied rather than just joining the legions?
Plus would using German warband be correct?
I know cavalry would be employed.

I’ll also be adding the auxiliary archer kit when that comes out, which is soon so I’m told!

[Diablo Jon]

Symmachiarii were barbarians who fought in native dress and style and served under their own tribal leaders (possibly with Roman officers attached). They signed up for a term of service but didn't receive citizenship at the end like Auxilla. Symmachiarii some of them Germans, are attested to in the Dacian wars.

[Tim Haslam]

Are they featured on Trajans column?

[Diablo Jon]

I believe these guys are generally consider to be Germans on Trajan's column.

[Tim Haslam]

Thought I’d seen those guys before!
 

[wmyers]

Their hair looks short.

Also, their shields, would they have painted their shields to distinguish them from non-Roman troops (and limit "friendly fire" casualties), possibly in a more uniform format?

[WuZhuiQiu]

Their hair looks short.

Possibly trimmed, to help identify them as being with the Romans? Alternatively, might their Suebian knots be on the left side?