Description

HEI shows that molten diamond is craftable with normal diamonds, but its only accepting rat diamonds(is this intended?).

Modpack version v0.52.0

No, only rat diamonds should me valid.
I could fix this on next release I think.

I think its possible to remove the oredict value gemDiamondRat form the normal diamond without any consciences, this would fix the Magma Crucible recipe.

And also is the Melting Crucible meant as an alternative?

is the Melting Crucible meant as an alternative?

Yes, this is earlier machine before TE crucible.

remove the oredict value gemDiamondRat form the normal diamond

No no, if i would remove it, lot of other recipes stop taking normal diamond as ingredient.