Eventing with non-fixed peaks?

My older sister has currently stopped riding, and gosh was she all about the un-needed fashion :uhoh: leading her to buy a rather pricey KEP Cromo helmet, which in turn has been taken over by myself.
While the helmet is lovely, comfortable and properly fits my head, the problem is that I have no idea if I can wear it XC.

I live in Ireland, and hope to do some eventing over the summer at lower levels, mainly unaffiliated. But all operate under Eventing Ireland/BE standard. The KEP has a non-fixed peak, and I have not got comments about it out XC schooling in places.

But honestly, I just don’t understand all the rules in place for EI. I dug through google searches, and this forum, but could find no answers! The cost of the helmet was phenomenal, and as would be purchasing a new skull cap or similar. Could anyone help me out?

Is there anyway to shoot an email or call to your governing body? Is it irish eventing or british eventing who sanctions your events. BE has made it clear that there are no fixed brims on xc. Dont know if the Irish have similar rules. Id find someone to email before going to an event just in case.