Replacement ipad

To my knowledge, iPad’s that are “replaced” as a warranty repair, or under the Applecare+ programme, are exchanged for a reconditioned device of the same model and specification; exchanges are not personalised with custom engraving.

Apple only supplies personalised/engraved product direct from manufacture. Unless your iPad has been replaced with a completely new item, engraving will not be available. As such, if you require your device to be engraved, you’ll need to arrange this with a third-party. Be aware that being non-standard, this alteration may of itself cause issues if you need to make a future warranty claim.

I don't know who told you that a "replacement" unit would have been engraved by Apple, but to my knowledge that's not true, sorry.

If you'd like, you can search for an engraver in your area and ask them.

Regards

Giulio