Full Idea
Soundness seems to be a notion essentially involving truth. At least I do not know how to fully express the soundness of Peano arithmetic without invoking a truth predicate.
Gist of Idea
Soundness must involve truth; the soundness of PA certainly needs it
Source
Volker Halbach (Axiomatic Theories of Truth [2011], 22.1)
Book Reference
Halbach,Volker: 'Axiomatic Theories of Truth' [CUP 2011], p.323
A Reaction
I suppose you could use some alternative locution such as 'assertible' or 'cuddly'. Intuitionists seem a bit vague about the truth end of things.