Miraflor is not a Spanish first name, it is a place name (a national reserve in Nicaragua) and a more usual place name when it is in the plural form Miraflores. It comes from the Spanish mira+flores, "(the place which)sees the flowers".
The variation Myraflor is impossible in Spanish, it is only a mistake, because in Spanish the letter Y is only a consonant or the conjonction y, "and", but it can never be used as vowel.
Moreover, the derivation from "milagrosa flordeliza" as Spanish origin is not correct. First, flordelisa (which should be the correct form in Spanish) is not a Spanish word; the Spanish word is "flor de lis". Since Flordelisa is found as first name, one could think in "milagrosa Flordelisa" (a saint named Flordelisa well-known because of her miracles), but there is not any saint/blessed/venerable Flordelisa.
And in the case of "milagrosa Flordelisa" or "milagrosa flor de lis" as the original forms, the derivation must be Milaflor, not Miraflor (in Spanish, L and R are two very different and differentiated sounds).
So, Miraflor is just a place name used as first name or a made up name (with Spanish elements).