I would propose a slight modification: that the clerk inform the witnesses of this requirement at the time of arranging for their attendance.
The purpose of that is obvious, but sometimes we have witnesses come with a prepared statement and they expect it is going to be sent around, but of course it cannot be unless it is in both languages. At least if they know when they are told they're coming they can arrange translation, or ask to have it translated before distribution.
For those who have been on this committee, sometimes it has been difficult when someone gives a presentation in one language and it is not available in written form in the other and members can be at a disadvantage afterwards in not having a written copy of the statement.