That's an interesting question?
Is there a Borg Language or do all the drones know all the languages of all the assimilated species ipso facto all drones speak whatever language which they are most comfortable with...
Which means that they no need of Universal translators.
They would only have universal translators as a pleasantry to the nearly assimilated, if at all.
Most nearly assimilated species would of course have their own universal translators but this still raises some curious points.