The answer from the Enrich help desk is:
We wish to inform that CIMB complimentary Lounge voucher is only for the main cardholder and not for the supplementary cardholder and for guests.
This is slightly confusing as the World Elite card doesn't appear to issue Lounge Vouchers but instead its the presentation of the card itself (plus boarding pass) which gets you into the lounge. It's not obvious how they would distinguish the main card holder from a supplementary card holder.
The other Enrich CIMB cards offer 5x or 10x Lounge access per year and this is administered through vouchers (presumably issued in the name of the main card holder).
No one can confirm how it works on the ground?