(History) Gallic/Celtic light horse ?

[Athos1660]

My interest in this question is purely historical as, from a gameplay pov, in-game Gallic 100-50 BC have Germanic foot tribes with Light javelin horse as allies. So any knowledge is welcome.

A certain Gaius Julius wrote once :

V, 57 : 'Meanwhile, almost every day, Indutiomarus, with all his horsemen, would range close to his camp (Labienus), sometimes to reconnoitre the situation thereof, sometimes to parley or to intimidate; and generally all the horsemen would discharge missiles (telum) within the rampart.’

https://topostext.org/work/683

Indutiomarus was a leader of the Treveri, a Celtic tribe of the Belgae group (hence, near Germanic tribes).
(Some translations use the verb 'skirmish' instead of 'range' in the extract above.)

Are there battle reports or some presumption of use of 'Light horses' in battles by the Celtic tribes living in Gaul ?