Latin Translation Question

I have heard that “Anima Sana in Corpore Sano” means “A sound mind in a sound body”
How would you convey the idea of a slightly less than sound mind in a slightly less than sound body? (not a direct translation of those words, but that general idea?)

I don’t know of a Latin adjective that means “slightly less than,” but paene means “almost,” so you could go with mens paene sana in corpore paene sano: an almost-sound mind in an almost-sound body. (You can interchange anima, “spirit,” with mens, “mind,” if you prefer. I have always heard the maxim using mens, but anima conveys effectively the same sense.)

My first-year law-school class almost adopted as its motto mens rea in corpore sano: a culpable mind in a capable body.

]i]Sanus/Mens Imperfectus in corpore imperfecto*.
An imperfect spirit/mind in an imperfect body.

I just realized that the OP and both responses so far (including mine) are mixing up genders. Animus is masculine and mens is feminine. Thus:

animus sanus [not anima sana] in corpore sano

mens imperfecta [not mens imperfectus] in corpore imperfecto

The OP would probably prefer animus, but anima isn’t wrong, is it? It just has a slightly different meaning.

Arguably. Animus means “the ‘rational’ or thinking part of the mind.” Animus means “breath, (hence) life, spirit, soul, ghost, air.” (These definitions come from William Harris, Latin Dictionary and Form Finder.)