If it’s a youth version helmet, it has the Snell CMR rating. The club might be skeptical because it doesn’t carry an Snell SA rating, but that rating is reserved for adult helmets. The CMR rating came out several years ago in response to the growing market for youth-specific helmets.
It shouldn’t be a problem at all, it should be legal. CMR helmets are legal (and mandatory some places for young drivers) and approved by the FIA/CIK.
It sounds like your club tech staff just isn’t totally familiar with the rating. If they give you a hard time about it, I would argue it, as the helmet IS totally legal.