For the French and British regulars the standards will be as per their historical counterparts.
The details of the flags for the european and sepoy regiments are not well known and so I've created some. I've decided on two per battalion. For the french I'll use a colonels flag may be with some colours in the quarter fields and a second flag showing the arms of the Compagnies Des Indes
For the british I'll use one with the arms of the Easty India company and a second with the facing colour of the regiment.
The volunteer battalions from either Monrovia or Wittenberg will have a first flag of the parent east india company and a second derived from their homeland.