[verb ない-form] + までも [noun] + で(は)ないまでも [na-adj] + で(は)ないまでも [i-adj 〜い → 〜く] + ないまでも
ないまでも means "even if not as far as X, at least Y". The first half names a higher level that isn't reached, and the second half names a lower one that still holds or should be met. It follows the ない-form of a verb, or で(は)ない after a noun.
The second half often carries せめて, すくなく少なくとも or くらい to mark the lower level.
These go beyond the plain verb form.
Most often the verb before ないまでも is ゆう言う: "I wouldn't go so far as to call it X, but…".
ないまでも belongs to writing and formal speech. In conversation the same idea is 〜~とまではいわない言わないけど or 〜~なくても、せめて.