How to get “almost everything” from “vix non quaedam” in this translation of a sentence from J.J. Fux?

Question

I'm trying to understand an English translation of a Latin sentence from J.J. Fux's Gradus ad Parnasum (written in Latin in 1725).

Here is the sentence:

Tuâ aviditate, quam tamen laudo, fit, ut vix non quaedam mihi praeposterè dicenda sint.

The musicologist Alfred Mann translates it:

Your eagerness, which still is praiseworthy, forces me to explain almost everything in the wrong order.

I understand the translation of the first five words -- literally, "Your eagerness, which I praise nevertheless." I'm trying to understand the grammar of the rest of the sentence, but I don't have much Latin.

I'm especially interested in the phrase "vix non quaedam" and how Mann gets to "almost everything." Literally, reading "vix" as "hardly," the Latin could be "hardly not certain things"; more idiomatically, maybe "hardly not a few." But I see "vix" can also mean "reluctantly" or "with difficulty." What is the best translation of "vix," here? And is the "non quaedam" functioning as a negative intensifier -- a sort of litotes?

Answer 1

quaedam praeposterè dicenda sunt (indicative voice for now, see below)

certain things-to-be-said are in-the-wrong-order (quaedam is neuter plural)

vix non quaedam mihi praeposterè dicenda sunt

not+not certain things to-be-said by me are arsy-versy.

Tuâ aviditate fit ut vix non quaedam mihi praeposterè dicenda sint.

By-your eagerness it-comes-to-pass that some of the things to be said by me be back to front. (be is a totally preposterous translation of the subjunctive after 'ut.') Mihi is a dative of agent, it replaces a, ab + ablative with periphrastic passives. Here is a clear explanation from OSU

( 'Dicenda' can be 'things to be said,' or 'things which need to be said.')

Tuâ aviditate, quam tamen laudo,

I think the 'tamen laudo' (which indeed I praise) and the litotes 'vix non quaedam' are attempts to be excessively polite, yet to show who is the boss.