I'd love to see pictures
Cream dilutes are definitely recognized by IALHA for Lusitanos, and I did get to see a beautiful double pearl Lusitano once (not sure what he got registered as, though!) Not sure if they'd have different rules for PRE Andalusians. I very rarely see any PRE Andalusians that are anything other than grey or bay.
Do you know if the horse you're riding is registered IALHA, ANCCE, or PRE Mundial?
All the breeder said is Black, Bay, Grey and now Chestnut are allowed in the ANCCE registry. I'm unsure if that includes or excludes dilutes...