word choice - Using "henceforth" to refer to future events, but from a "past perspective"

Henceforth means "from here forward". With a present or present construction, it points the reader forward from the time of utterance. In your case, that would mean "from now forward", the present in which you write and your readers read. This is not, I think, what you want. The acknowledgements occurred before the present.

You could resolve this by casting your verb in the past, the time referred to, and saying "The importance of Foo was thenceforth acknowledged . . ."—thenceforth meaning "from there (i.e. then) forward". But while henceforth has a modest currency in academic and other highly formal writing, thenceforth has an inescapable odour of archaism. Again, not what you want.

I suggest KISS:

Since then, the importance of Foo has been acknowledged . . .

It's acceptable both formally and colloquially.