an easy way might be to put a [bang~] in a subpatch, so that it is
triggered after the [env~ ] objects, and then connect each [env~] to the
right inlet of a [f ]...then you
can bang the floats with [t b b] from the [bang~]
well, but the [bang~] will have the same problem: it might trigger
before or after [env~] has updated it's value.
but of course you proposal to use another source for synching the
outputs is the way to go.