등's definition is: a bound noun used to indicate that there are other things of the same kind as the thing that was just mentioned.
우크라이나 수도 키우프 제2 도시 하리코프에 집중 포격을 가하는 등 공격의 고삐를 늦추지 않았습니다.
I can't understand the sense of 등 in this sentence.
There is a concentrated bombardment on Kiev and Kharkiv, and (?) they don't want to slacken the reins of the attack.
How is a bombardment of the same kind as alleviating the intensity of an attack?
This is your mistranslation. You need to interpret the two clauses separately.
a bound noun used to indicate that there are other things of the same kind as the thing that was just mentioned.
“등” is like “and et cetera; and so on,” in English, implying other more things of the same kind. “공격의 고삐를 늦추지 않았습니다.” is not what the “등” is implying.
When “등” is used with a clause (a verb), it works like a participle phrase (adverbial) in English: it translates to “Verb-ing … and so on,”.
“우크라이나 수도 키우프 제2 도시 하리코프에 집중 포격을 가하는 등,” translates to “Bombarding on Kiev and Kharkiv and so on,”.
“고삐를 늦추다” (literally “to slacken/loosen the reins”) is an idiom that means “to lower the intensity,” by analogy with horse-riding. A horse stops running if you slacken the reins.
“고삐를 늦추지 않았습니다” is a negation of that: “not to lower the intensity; to increase the intensity.”
And with “공격의” (“of the attack”), it means “they did not lower the intensity of the attack,” which is the opposite of “alleviating.”
