Past / Past Perfect

First, the victorious Soviets could satisfy themselves that they [had not deceitfully concealed / had not been deceitfully concealing / never deceitfully concealed] their objective of founding a Communist state, or their antipathy to those they regarded as reactionaries or anti-revolutionaries, or their intention to remold these and the rest of the non-proletarian classes under their auspices. All of these [did, at one time or another, find / had, at one time or another, found] their way into Soviet agitprop. This being said, the Soviet Communist Party most certainly often [couched / had couched] these views in very hazy and amorphous terms, such that few could have foretold with confidence their subsequent implications.

Can someone who is very patient go through this paragraph and kindly explain to me the implications of the different choices of tense within each of the pairs of brackets [ ]? I thank you for your time in advance.

Do I use the past perfect tense only when referring to a point 'in the past before the past'? Can I use it when referring to an event that had begun at a point 'in the past before the past' and that continued through 'the point of the past'? I am sorry if I am so convoluted that I do not make much sense.