1. What does 'or in other no less florid and true utterances' mean? (Has it not been dinned into us by proverb and sermon and fable that we never prize the music till the sweet-voiced bird has flown -- or in other no less florid and true utterances? )
2. What does 'against the hour for the nightly game' mean? (The boys were knocking the balls idly into the pocket against the hour for the nightly game.)
3. What does 'a band slipped' mean? What is 'band' in machinery? (A band slipped, a spring was touched, the gear was ajusted and the wheels revolve in their old orbite.)
4. What does 'dolcy far nienty' mean? (And there's nothing doing in the shoe store but dolcy far nienty.)
5. What does 'left him even in such high places' mean? (Keogh slipped into the sinecure of American consulship with the ease that never left him even in such high places.)
I'll take a stab at 1. through 3.
1. "voiced bird has flown" is an example of a florid (showy) and true (known) utterance?
2. 'against the hour for the nightly game' probably means, fight against time - slow time dowm - so they could play (pool or billiards) longer.
3. In an engine or piece of machinery, a band, like a belt, is a flat, slender piece of material, usually rubber. It slipped means, it came out of place.