A day or two after the post you quote I did some more runs, all or almost all on T8. On my notes I can see that I opened 57 games, found Chiltara 18 times without any gemstone dropping. I stopped farming and when it became clear that the Altar wouldn’t be in non season.
If I’m not mistaken the chance of getting the item is just as good in normal as in higher difficulties.
For example there is this discussion from March 2023:
1 Like