Also relevant is this great post by Bhante Brahmāli:
“Deathless”, for instance, is supposed to be a translation of amata . Mata means dead and the a is a negative prefix. A common use of such prefixes is as a privative, that is, to show the absence of the term they are associated with. Amata should therefore be translated a “freedom from death”. That this is correct can be seen from it’s usage in MN26, where it is clear from the context that the Buddha is searching for the freedom from death, not some sort of deathless state.
I don’t even know what the Pali word behind “realm” is supposed to be, and I am not sure if there even is one. But the Pali word behind “element” is dhātu , and “element” is not really a satisfactory rendering, at least not in this context. For instance, in the suttas you have the nirodha-dhātu , which would then be the “element of cessation”. This is fine, but only if we expand our normal understanding of “element”. A better translation might be “the property of cessation”. In the same way, amatadhātu can best be rendered as “the property of freedom from death”.
If you look for eternal bliss, that’s what you will find, except you will be disappointed. Your view will decide how you interpret your experience. If you get it wrong, you will get stuck. So yes, have an open mind, but remember that nibbāna means extinguishment, not eternal bliss.
The danger in reification of nibbāna is, I think - if one keeps practicing with the hope of arriving at an eternally happy state, one will never fully give up craving for existence, and that may prevent the practitioner from the break through to stream entry.