Hi,
Whilom wrote:Jupiter put on our two wallets:
Here,
impono takes a dative for where you put the thing on, so it's "Jupiter has put two wallets on us."
Our own wallets having been filled with faults after he puts them back,
propriis here goes with
vitiis, while
repletam is singular and so agrees with one of the wallets.
post here is used as a preposition governing
tergum. It's something like "he has put [the one] filled with our own vices behind [our] back."
He hung up with grave vices belonging to another before our heart.
the only thing here is that
gravem here goes with the other wallet -- something like "he has hung [the one] heavy with others' [vices] before [our] breast."
We are not able to see these evil things;
hac re here means "by this thing" = "as a result", while you missed
nostra, so "by this thing we are not able to see our own evils."
The others fail as soon as, we are censors.
In Latin, conjunctions don't necessarily come first, so "as soon as other fail,..."
I hope that helps.