Are the QIAseq miRNA NGS 5’ Adapter and QIAseq miRNA NGS RT Initiator compatible with the QIAseq miRNA UDI kits?

No, these are not compatible. A UDI-specific 5’ adapter (UDI 5’ Adapter) and UDI-specific RT Initiator (UDI RT Initiator) are included in each QIAseq miRNA UDI kit.