Quote Originally Posted by wonlon View Post
Does these 3 phrases all follow "как Петру I удалось"? like
не понятно, как Петру I удалось реализовать грандиозные по замыслу планы,
не понятно, как Петру I удалось поставить на дыбы страну
не понятно, как Петру I удалось за несколько лет построить столицу на болоте.

It is difficult to understand how Peter the Great succeeded in implementing his grandiose plans, succeeded in making the country stand on it's hind legs, succeeded in building Saint Petersburg on the swamp.
They do.

Quote Originally Posted by wonlon View Post
Do you mean "no other usage except this idiomatic meaning"? I previously doubted about whether it means "... was also shown in the action".
I'm sure he did mean what you suggested. However, I'd strongly argue against that. First, this "-ся form of "сказать" is absolutely irrelevant to the meaning of "сказать and has no over usage except this idiomatic meaning.". Definitely not true. This phrase that probably very single Russsian learns in their childhood immediately comes to mind:

Долго сказка сказывается, да не скоро дело делается. It clearly means "to be said" here and don't be distracted by a slightly changed form of the word there. It's still exactly the same word but in imperfective form. It's also a compelling proof that this word can have other usages.

Moreover, the meaning of the word in the passage you want help with comes directly from just this "to be said", it's just used figuratively there. If you translate that with this in mind, well, I guess it'd make perfect sense in English as well.

Незнание разумной золотой середины сказались и в действиях - Their ignorance of the golden mean was said in their actions.

So yep, you can think of this as "was also shown in the action". One of the synonyms of the word is проявляться after all. The thing is, you kind of should not. Don't take me wrong, this word still can adopt this meaning in many cases but now it's usually, just as Alex80 said, means "to have an effect on...", "influence", "affect".

Their ignorance of the golden mean affected/influenced their actions.

Other examples:

Его махинации сказались на его репутации - His schemes affected his reputation.
Травмы сказались на игре команды - The injuries affected the team's play.

Note that in this meaning it's usually about "bad influence".