"Heldbredelsen" is not a word that's used in danish. It's a correct word and it does mean cure but it's just never used. I mean never. This is the first time I have ever read it and I have never heard anyone say it.
I have heard the word "helbredelse" in a radio interview on Danmarks Radio just a few weeks ago.
The thing to say would be "hvad er behandlingen" (what is the cure/ treatment)
Actually, the TTS pronounces it as a Dane (from the east, at least) would when speaking at average/a little above average speed. The 'd' in 'hvad' is cut off so that the word sounds like "hva'" and the 'er' just sounds like an a. It is not an ideal pronunciation for people trying to master the soft 'd', I agree on that.