How often have you heard a native speaker say "very much true"?
Grammatically, it is perfectly valid to say something is "very much xxx", where xxx is an adjective.
Semantically, it is a superlative - intepretation depends on what the proposition is that the statement "it is very much true" is referring to.
Some propositions are either true or false - e.g. today is Saturday - there's not much room for this to be only "partly" true, so equally it wouldn't make sense to say it is "very much true".
There are, however, plenty of propositions which may legitimately be argued to be only partly true - e.g. it is a cold day today - the truth or falseness of this statement depend partly on the actual weather, and partly on the perceptions of those complaining about it.
An Alaskan might say "false, it's not cold today", to which a Floridian might respond, "what? no! it's very much true!"